The correct use of diacritical marks is considered by many editors an important part of writing an encyclopedia. Under the Wikipedia:Manual of Style § Spelling and romanization guidelines, "The use of diacritics for foreign words is neither encouraged nor discouraged; their usage depends on whether they appear in verifiable reliable sources in English". The current Wikipedia practice on this issue is generally in line with other English-language encyclopedias such as Britannica, and with the recommendations of influential style guides such as The Chicago Manual of Style. Particular care is taken to spell personal names correctly. In some other cases, such as with loanwords, the common spelling in other English sources is normally used.

Several reasons for the current practice have been presented in addition to external guides and practice: Accuracy (the lack of diacritics in foreign names is considered a grammatical error or misspelling by several reliable sources), consistency (following the "house style" instead of case-by-case use of the most common spelling), harmlessness (the diacriticless spelling is deducible from the proper noun, but not vice versa), pronunciation guidance, informativeness (an encyclopedia's primary purpose is to educate the readers by providing accurate, complete and trustworthy information) and respect (particularly with living people, knowingly misspelling a name could be both unencyclopedic and unethical).

The proper names of bands, brands, companies, institutions, organizations, venues, et cetera, are written with the appropriate diacritical marks. Some of these subjects have an established English title, which is preferred.

• Médecins Sans Frontières volunteers were seen eating Häagen-Dazs in a Škoda while Queensrÿche opened for Motörhead at the Helsinki Ice Hall.

In citations and quotations, diacritical marks are used as they appear in the source.

• "Thorbjørn Jagland". The Guardian.
• "Questions for Thorbjorn Jagland..." The New York Times.
• "Nobel committee head Thorbjoern Jagland..." The Courier-Mail.
• "Visit to NATO by Mr. Thorbjörn Jagland..." NATO.

Some English words have diacritics. The form preferred by most English-language sources is commonly used. Sources typically keep the diacritical marks when they make a crucial difference to pronunciation or help avoid confusion. Often sources are divided and both forms are considered acceptable, as is the case with café.

• debut, premiere, regime, role...
• doppelgänger, pâté, piñata, résumé...

Foreign words are written in italics with the correct diacritical marks (and capitalization).

• dāna, Führerprinzip, omertà, pied-à-terre...

Whenever the most common spelling in English-language reliable sources is the person's real name, or the name with the diacritical marks simply omitted, the proper name (with the diacritics) is normally used. Exceptions include some historical persons (as foreign personal names were often anglicized in the past) and naturalized citizens who have adopted a different spelling of their name. Weight can and should also be given to the preference of the living subject (compare to capitalization: danah boyd).

• Salvador Dalí, Dominik Hašek – not "Salvador Dali" or "Dominik Hasek" which are the common spellings in English (non-encyclopedia) sources
• Ferdinand Magellan, Napoleon – not "Fernão de Magalhães" or "Napoléon" as these persons have anglicized names
• Martina Navratilova, Stanislaw Ulam – not "Martina Navrátilová" or "Stanisław Ulam" as these persons adopted naturalized spellings of their names

An established anglicized name is preferred (even if it merely drops the diacritical marks). In other cases, articles are written with the native proper name and the appropriate diacritics.

• Nuremberg, Gothenburg, Montreal, Istanbul...
• Düsseldorf, Saint-Étienne, São Paulo, Chișinău...

Unless a more common English title exists, the original title with the correct diacritical marks (and capitalization) is used.

• Garçon à la pipe, Götterdämmerung, À nous la liberté, Mekanïk Destruktïw Kommandöh...

English-language reference works, especially encyclopedias, retain diacritics in non-anglicized foreign names that are commonly spelled without the marks in other sources. The following tables contain some examples.

Several reasons for the current practice have been presented:

• Accuracy: The proper use of diacritical marks can be considered part of being as accurate and precise as possible. The style guides of several reliable sources consider the lack of diacritics in foreign names a grammatical error or misspelling. The Journal of Paleontology lists "not putting in diacritical marks in foreign words or names" among common errors of grammar in English.^[6] K. R. Norman writes that "diacriticals are a matter of spelling, not of aesthetics, or of whim, and result from an attempt to make the Roman alphabet cope with a sound pattern that needs an alphabet with more than 26 letters. Omitting diacritics is therefore a matter of misspelling and inserting them is a matter of correct spelling. It is not just a way of placating some pedantic academic who is a stickler for accuracy."^[7] The inclusion of the correct diacritics also avoids changing the meaning of the word, which could be embarrassing both to the project and to the subject: Afrikaanse Hoër Seunskool is not the Afrikaans Whore School for Boys. In William Safire's book Watching My Language, James D. McCawley called the practice of omitting diacritics in foreign names "disgraceful and slovenly" and noted how the telenovela Los Años Perdidos (The Lost Years) became Los Anos Perdidos (The Lost Assholes) in Chicago newspapers.^[8]

• Consistency: Consistency in the usage of diacritics is recommended by practically all English style guides that have commented on the matter. Case-by-case use of the most common spelling inevitably leads to heavy inconsistency, which can mislead the reader by wrongly insinuating that a name has been anglicized or does not have any diacritical marks. It would be detrimental to the encyclopedia to confuse some of the Jönssons and Jónssons with Jonssons. Bill Walsh, a copy chief at The Washington Post, writes in his style book Lapsing Into a Comma that "if your publication has the time and resources to use accents and other diacritical marks correctly, go for it" but "if you can't use them consistently and correctly, you shouldn't use them at all."^[9]

• External guides: Support for the correct use of diacritics is overwhelming in influential English style manuals such as The Chicago Manual of Style. Along with scholarly publications, major organizations and institutions, such as the European Commission, Library of Congress, National Geographic Society and UNESCO, stress the importance of including the appropriate diacritical marks.

• External practice: External practice can be an argument both for and against diacritics. Online newspapers, which often equate to most or only English-language sources available, tend to omit the marks due to the technological issues with wire services, to reduce the workload and meet the deadlines, to avoid using them incorrectly or inconsistently or to target an American rather than international audience. Many newspapers blame the Associated Press for the lack of diacritics.^[10] Higher quality papers edit the AP newswires to include the diacritics at least for some languages. The sources most relevant to Wikipedia, like other encyclopedias and reference works, use them correctly in a similar fashion to us. The lack of highest quality sources for a certain topic, combined with an abundance of news stories, does not mean we should stray from encyclopedic practice. The Chicago Manual of Style notes that "while common usage can excuse many slipshod expressions, the standards of good usage make demands on writers and editors."^[11]

• Harmlessness / net benefit: While the proper use of diacritics can sometimes be time-consuming for editors, the marks can be considered harmless for the readers as a diacriticless spelling (such as "Hasek") is deducible from the proper name (Hašek), but not vice versa. There is no indication that readers find the marks confusing. The St. Louis Post-Dispatch asked its readers whether diacritical marks are necessary for newspaper/online stories, with over 80% responding that they are.^[12] On Wikipedia, redirects are created from all common spellings as standard practice. The diacritical marks are also removed for sorting and ignored by search engines. In the past, the foreign character template was often used when a common spelling did not merely replace a modified letter with the closest resembling basic Latin character, such as with Gerhard Schröder.

• Informativeness / pronunciation guidance: The primary purpose of an encyclopedia is to provide accurate and trustworthy information. The reproduction of popular but less accurate and informative spellings can be seen as withholding of information or spreading of common misconceptions, and as such contradictory with an encyclopedia's educational goal. The information contained in the diacritical marks is important in many ways. It does not merely educate the reader in the correct spelling, but also in the proper pronunciation. Often the marks make a crucial difference. Résumé is not pronounced like the verb resume and Jiří Novák not like "Jerry Novak" ("Yirzhi Novaak").

• Respect: Correct spelling of proper names, especially those of living individuals, may be considered a matter of respect. Knowingly misspelling a name could thus be both unencyclopedic and unethical. The Merriam-Webster's Guide to International Business Communications states that "it is generally somewhat dangerous to omit diacritical marks. Norwegian Mr. Høst will not appreciate at all being called "Mr. Host"."^[13] Aly Colón of the Poynter Institute writes that "I want my name spelled right. People usually do." He argues that "spelling someone's name right has ethical implications. After all, a fundamental element of ethical journalism involves accuracy."^[14]

• American Journal of International Law: "Please retain all foreign characters and diacritical marks necessary for proper spelling."^[15]
• Bioscience Horizons: "All manuscripts must: [...] have correct diacritics for non-English words"^[16]
• Journal of Baltic Studies: "All non-English words should be in italic script, and along with all non-English names, they should be spelled with accents and diacritical marks included. Languages native to the Baltic region shall be rendered in the full orthographic shape, including diacritics and special letters."^[17]
• Journal of Paleontology: "Pay strict attention to diacritical marks in names and words [...] Titles in languages using the Roman alphabet are not translated [...] Common errors of grammar are: [...] not putting in diacritical marks in foreign words or names."^[6]
• University of Alabama Press: "If your word processing program can render special characters or diacritical marks, please use them [...] Ensure that all foreign names and words have appropriate diacritical marks."^[18]
• University of Virginia Press: "Use diacritics and special letters correctly in all place-names and names of individuals."^[19]
• Wiley-Blackwell: "German: Use ß (eszett) for ss, but only in lower case (and note that not all ss are ß); in caps (and small caps), SS is always used. Use umlauts over ä, ö and ü rather than using the respective diphthongs ae, oe and ue. Remember that, in German, all nouns have initial caps (e.g. ein Haus, das Sein) and they should retain these when italicized. French: Upper-case letters carry accents, e.g. RÉSUMÉ. The exception is the preposition à, e.g. A la porte."^[20]

• American Society for Horticultural Science: "Names of authors are given according to the preferences of the author(s)—full names (not initials) are encouraged. The spelling of names of foreign authors is in the native spelling with diacritical marks (if present) [...] Retain diacritical marks in authors’ names, street addresses, and literature citations. Do not use them for names of cities and countries, unless there is no English equivalent (e.g., use “Spain,” not “España,” or use “Cologne,” not “Koln”)."^[21]
• American Sociological Association: "Because many manuscripts are now being prepared with word processing systems that contain software with special characters (including diacritical marks and alphabetical characters that do not normally occur in English), use these characters when keyboarding foreign words. Try to maintain consistency throughout the manuscript: If special characters are used for some words, they should be used for all words that conventionally would be accented (Québec, Montréal, Palais des Congrès de Montréal, l'Hôtel-Dieu)."^[22]
• British Council: "Accent marks: Retain when using foreign names, whether personal, geographical, or company titles [...] Personal names: When you cite a person's name, it is important that you spell the name correctly, so check, even if the name appears to be a simple one."^[23]
• Council of Science Editors: "Retain diacritics in personal names and place names if the names have not been anglicized. Word-processing programs now offer a wide variety of characters combining letters and the applicable diacritics, but such characters must be checked after typesetting to ensure that the desired characters appear."^[24]
• IEEE Computer Society: "Use accents in anglicized non-English terms when important for pronunciation, to avoid confusion with another word, or where context makes it unclear. Use accents in non-English names, especially names of individuals. In general, lean toward the author’s preference."^[25]
• National Geographic Society:
  • "Foreign terms that have not become anglicized should be set in italics on first use and given proper accents if from a Latin alphabet. A word may become roman and still keep its diacritical mark: mañana. Anglicized words may be italicized on occasion to emphasize their foreign flavor: mañana, kat."^[26]
  • "Place-names from foreign languages appear in roman; retain diacritical marks if original is from a Latin alphabet except in commonly anglicized names: Montreal, Quebec, Istanbul. If a place-name is transliterated from a non-Latin alphabet, diacritical marks are generally not used except on atlas and supplement maps. Place-names from Arabic or Cyrillic follow the common anglicized spellings. Follow NGS atlas, then the Board on Geographic Names."^[26]
  • "Languages with Latin alphabets: Retain the original diacritical marks (accents, apostrophes, dots, cedillas, glottals, etc.) in unanglicized words in the following languages: Czech, Danish, Dutch, Finnish, French, German, Hawaiian, Hungarian, Icelandic, Irish, Italian, Latvian, Norwegian, Polish, Portuguese, Slovak, Spanish, Swedish, and Turkish. Some anglicized terms from these languages also retain their accents (follow Webster’s)."^[26]
  • "Modern style is to retain accents on French capital letters, especially in French place-names, as in Île de la Cité. The word à does not carry an accent when capitalized. In Spanish retain accents on capital letters. Use accents on American Indian words as well as on words of other indigenous peoples if the language is written in the Latin alphabet. Although Vietnamese is written in the Latin alphabet, the number of accent marks can be distracting and may therefore be omitted."^[26]
• Society for American Archaeology: "Use standard orthographies, including diacritical marks, and explain unusual symbols [...] For both journals, include all common accents for French, Spanish, Portuguese, German, etc., in the text and in the References Cited section. Be sure the accents are clearly marked, accurate, and consistent. Pay particular attention to proper names and titles of works (the rules of placement of accents in Spanish hold for all place names in Spanish, even on words that were hispanicized from other languages such as Nahuatl or Mayan, except for words that have accepted English spellings). Examples: Teotihuacan, Chichén Itzá, Copán, Kaminaljuyú."^[27]
• UNESCO: "When reproducing foreign words it is important to include the diacritical marks that are placed in various languages above or beneath certain letters (e.g. tilde in Spanish) and that have the effect of modifying their pronunciation. However, the hamza (') and ayn (`) are not used in Arabic transliterations (Shiite, not Shi'ite)."^[28]

• European Commission: "Personal names should retain their original accents, e.g. Grybauskaitė, Potočnik, Wallström."^[29]
• European Union: "Use the special characters available. Avoid all transliteration (‘ss’ for ‘ß’, ‘ue’ for ‘ü’, etc.)."^[30]
• IAEA: "A surname, even of several words, should always be given in full. Accents and other diacritical signs should be retained where they are known. Accents are omitted from Spanish names in block capitals, with the exception of the Spanish tilde (Ñ), which must be retained."^[31]
• United Nations Development Programme: "Respect use of accents and special characters in proper names. EXAMPLE: Zéphirin Diabré."^[32]
• World Bank: "Also called diacritical marks, accents are to be kept in foreign words in their original form, except in capitalized style."^[33]

• Art Institute of Chicago: "Retain all diacritical markings in foreign languages—including those over capital letters."^[34]
• Beinecke Rare Book and Manuscript Library: "Include proper use of diacritics to the extent allowed by the current keyboard capabilities."^[35]
• Carnegie Museum of Natural History: "Special attention must be given to precise and accurate spelling of all place names and foreign language words with full diacritical marks included."^[36]
• Library of Congress: "The Library has consistently followed a policy of reproducing the bibliographic information in as precise a form as possible. This has meant reproducing all diacritical marks and special characters used in other roman alphabet languages and other alphabets where needed."^[37] "Note: Prior to January 2006 catalogers did not add a diacritic to initial capital letters in French, Spanish, and Portuguese. This exception no longer applies. With respect to capital letters appearing at the beginning of names or words, add diacritics according to the usage of the language."^[38]

• United States Agency for International Development: "Diacritical marks are an essential part of some proper names, geographic names, and foreign words. Do not omit them. Insert them in ink if the typewriter does not have such marks. Generally, do not use diacritical marks with English words."^[39]
• United States Government Printing Office: "Diacritical marks are not used with anglicized words. Foreign words carry the diacritical marks as an essential part of their spelling."^[40]

• The Economist: "On words now accepted as English, use accents only when they make a crucial difference to pronunciation: cliché, soupçon, façade, café, communiqué, exposé (but chateau, decor, elite, feted, naive). If you use one accent (except the tilde—strictly, a diacritical sign), use all: émigré, mêlée, protégé, résumé. Put the accents and cedillas on French names and words, umlauts on German ones, accents and tildes on Spanish ones, and accents, cedillas and tildes on Portuguese ones: Françoise de Panafieu, Wolfgang Schäuble, Federico Peña. Leave the accents off other foreign names."^[41]
• The Guardian: "Use on French, German, Portuguese, Spanish and Irish Gaelic words (but not anglicised French words such as cafe, apart from exposé, lamé, résumé, roué). People's names, in whatever language, should also be given appropriate accents where known. Thus: "Arsène Wenger was on holiday in Bogotá with Rafa Benítez"^[42] "Try to include diacritical marks if bands use them in their name, no matter how absurd: Maxïmo Park, Mötley Crüe, Motörhead, etc"^[43]
• The New York Times: "Accent marks are used for French, Italian, Spanish, Portuguese and German words and names. [...] Do not use accents in words or names from other languages (Slavic and Scandinavian ones, for example), which are less familiar to most American writers, editors and readers; such marks would be prone to error, and type fonts often lack characters necessary for consistency. Some foreign words that enter the English language keep their accent marks (protégé, résumé), others lose them (cafe, facade). The dictionary governs spellings, except for those shown in this manual. In the name of a United States resident, use or omit accents as the bearer does; when in doubt, omit them. (Exception: Use accents in Spanish names of Puerto Rico residents.) [...] Some news wires replace the umlaut with an e after the affected vowel. Normally undo that spelling, but check before altering a personal name; some individual Germans use the e form."^[44]
• The Times: "Give French, Spanish, Portuguese, German, Italian, Irish and Ancient Greek words their proper accents and diacritical marks; omit in other languages unless you are sure of them. Accents should be used in headlines and on capital letters. With Anglicised words, no need for accents in foreign words that have taken English nationality (hotel, depot, debacle, elite, regime etc), but keep the accent when it makes a crucial difference to pronunciation or understanding - café, communiqué, détente, émigré, façade, fête, fiancée, mêlée, métier, pâté, protégé, raison d'être; also note vis-à-vis."^[45]

• AMA Manual of Style: "English words once spelled with accent marks (eg, cooperate, preeminent) now are written and printed without them. Consult the most recent edition of Merriam-Webster's Collegiate Dictionary to resolve questions about whether a word should retain its accent. In general, English words in common usage should be spelled without diacritical marks. Accent marks should always be retained in the following instances: Proper names: Dr Bönneman is a Pew Scholar in the Biomedical Sciences [...] When it is desirable to show the correct spelling in the original language: Köln (Cologne) [...] In quotations: "Más vale pájaro en mano que cientos volando" [...] In terms in which accent marks are retained in current use (consult dictionaries) [...] To show pronunciation and syllabic emphasis"^[46]
• AP Stylebook: "Use accent marks or other diacritical marks with names of people who request them or are widely known to use them, or if quoting directly in a language that uses them: An immigration officer spotted him and asked a question: 'Cómo estás?' How are you?"^[47]
• APA style: "[Reference list:] The best way to ensure that information is accurate and complete is to check each reference carefully against the original publication. Give special attention to spelling of proper names and of words in foreign languages, including accents or other special marks [...] [Manuscript format:] Special characters are accented letters and other diacriticals, Greek letters, math signs, and symbols. Type all special characters that you can, using the special character functions of your word-processing program."^[48]
• The Chicago Manual of Style: "Foreign words, phrases, or titles that occur in an English-language work must include any special characters that appear in the original language. Those languages that use the Latin alphabet may include letters with accents (diacritical marks), ligatures, and, in some cases, alphabetical forms that do not normally occur in English."^[49] "Although French publishers often omit accents on capital letters (especially A) and may set the ligature Œ as two separate letters (OE), all the special characters needed for French—including capitalized forms—are available in most software and in most fonts, and they should appear where needed in English works. This practice, advocated by the Académie française, is helpful to readers who may not be familiar with French typographic usage."^[50] "Although umlauted vowels are occasionally represented by omitting the accent and adding an e (ae, Oe, etc.), the availability of umlauted characters in text-editing software makes such a practice unnecessary."^[51] "Accented capitals, sometimes dropped in Portuguese running text, should always be used when Portuguese is presented in an English context."^[52]
• The Christian Writer's Manual of Style: "For foreign words that have become common in English, no common rules can be given for when to retain an accent, or diacritic, and when to drop it. The language is in flux. It is becoming more common, for example, to see the acute accent and diacritics being dropped from the words cliché, café, and naïve--thus, cliche, cafe, and naive. In many cases, the accent should be retained to avoid misreading: for instance résumé (or resumé) instead of resume; pâté instead of pate [...] Accents and diacritics should be retained in foreign place names (such as São Paulo, Göttingen, and Córdoba) and personal names (such as Salvador Dalí, Molière, and Karel Čapek)."^[53]
• The Elements of Typographic Style: "Recent digital technology has made it possible for any typographer to create special characters on demand — a luxury most have been without since the seventeenth century. Prepackaged fonts of impeccable design, with character sets sufficient to set any word or name in any European and many Asian languages, and the software to compose and kern these characters, are also now available even to the smallest home and desktop operations. Yet there are large-circulation newspapers in North America still unwilling to spell correctly even the names of major cities, composers and statesmen, or the annual list of winners of the Nobel Prize, for fear of letters like ñ and é. Neither typographers nor their tools should labor under the sad misapprehension that no one will enjoy or even mention crêpes flambées or aïoli, no one will have a name like Antonín Dvořák, Søren Kierkegaard, Stéphane Mallarmé or Chloë Jones, and no one will live in Óbidos or Århus, in Kroměříž or Øster Vrå, Průhonice, Nagykőrös, Dalasýsla, Kırkağaç or Köln."^[54]
• Lapsing Into a Comma: "If your publication has the time and resources to use accents and other diacritical marks correctly, go for it. But I maintain that it's impossible to use them consistently and correctly in a deadline-intensive medium such as daily newspaper journalism. If you can't use them consistently and correctly, you shouldn't use them at all."^[9]
• Merriam-Webster's Manual for Writers and Editors: "Diacritical marks should be added to foreign words if the author has omitted them."^[55]
• MHRA Style Guide: "(a) When a word or, more often, an expression is still felt to be foreign (and an objective decision is not always possible), all diacritics should be retained, e.g.: aide-mémoire, ancien régime, à la mode, Aufklärung, la belle époque, bête noire, cause célèbre, déjà vu, éminence grise, Führer, lycée, maître d’hôtel, papier mâché, pièce de résistance, più, raison d’être, señor, succès de scandale, tête-à-tête [...] (b) Words ending in -é retain their accent: blasé, café, cliché, communiqué, exposé, fiancé (also fiancée). In such words, any other accents are also retained, e.g.: émigré, pâté, protégé, résumé. We recommend that, except as provided for in (b) above, diacritics should be dropped in the case of words that have passed into regular English usage, e.g.: chateau, cortege, creche, crepe, debacle, debris, decor, denouement, detente, echelon, elite, fete, hotel, matinee, naive, precis, premiere, regime, role, seance, soiree [...] Accents should be retained on capitals in languages other than English, e.g.: le Moyen Âge, Éire, el Éufrates, Ólafsson. However, the French preposition à may drop the accent when capitalized (A bientôt! ‘See you soon!’)."^[56]
• Mind the Gaffe: "With names - most often foreign names - containing diacritics (accent marks), you should reproduce those diacritics faithfully. Today almost any word processor can produce the commoner diacritics. So, the Spanish Basque golfer is José María Olazábal; the Turkish patriot is Mustafa Kemal Atatürk; the French politician is François Mitterrand; and the English novelist is Charlotte Brontë."^[57]