A set index article (SIA) is a list article about a set of items of a specific type that also share the same (or similar) name. For example, Dodge Charger describes a set of cars, List of peaks named Signal describes a set of mountain peaks, and List of ships of the United States Navy named Enterprise describes a set of ships.

Being a set of a specific type means that the members of the set have some characteristic in common, in addition to their similarity of name. A list is an SIA only if both criteria for inclusion of an item in the list are met. For example, every entry in a list of earthquakes might include the word "earthquake", but that alone does not mean that the list is an SIA. If earthquakes were assigned names similar to how tropical storms are named, then List of earthquakes named X could be a set index (assuming of course that there are multiple earthquakes with the same name).

Fundamentally, a set index article is a type of list article. The criteria for creating, adding to, or deleting a set index article should be the same as for a stand-alone list. The style of a set index article should follow the style guidelines at Wikipedia:Stand-alone lists. A set index article can be tagged with {{Set index article}}. Notably, a SIA is not necessarily titled a "List", it can be titled as a partial disambiguation, e.g., Star (newspaper).

A set index article is not a disambiguation page:

• A disambiguation page is a list of things (possibly of different types), that share the same name (or similar names).

  It is formatted to best help the reader in navigating to the topic being sought.

• A set index article (or SIA) lists things only of one type, and is meant to provide not only navigation, but information as well.

  Just as with a typical list article, it may have metadata and other extra information about any of its entries, in contrast to the guidelines of what not to include on disambiguation pages.

An SIA need not follow the MOS formatting rules for disambiguation pages; in contrast to many restrictions stated the disambiguation page guidelines such as those regarding red links, an SIA may contain:

• red links to help editors create articles on notable entries, and
• references (to document the respective bases for inclusion of entries in the list).

Occasionally there is both a disambiguation page and a set-index article organized about the same term. If the disambiguation page bears the term as its title (as is the case with Signal Mountain), then the set index article can be named "List of XXXs named YYY"; the example of List of peaks named Signal is an example of this.

If the circumstances allow a choice between having the (bare or unqualified) term link to a set-index page or to the disambiguation page, that term usually should be assigned as the disambiguation page's title because the disambiguation page-type accommodates the broadest variety of uses. (Nevertheless, in the rare cases where the set index article is considered the primary topic, it may be named with that term (without further qualification), with the disambiguation page accordingly being titled "YYY (disambiguation)" per guideline on disambiguation page naming.)

A disambiguation page should not be reclassified as a SIA (e.g., on the basis that its entries all happen to be instances of a single type). As an example, Western State Hospital is, correctly, categorized as a disambiguation page even though each of the articles it links to is literally a hospital (rather than some other type of building – or legal entity, titled work, mental state, etc., ad infinitum).

How to tell whether the page could be a set index article

Similar names?	Similar subjects?	Type of page	Example
Y Yes	Y Yes	Set index article	Dodge Charger
Y Yes	N No	Disambiguation page	Charger
N No	Y Yes	Ordinary article, stand-alone list, or broad-concept article	List of Dodge vehicles

A set index article (a list of items of a specific type that share the same name, or sufficiently similar ones) may be one or more of the following:

• Notable list:

  The list topic has been discussed as a group or set by independent reliable sources.

  The individual entries needn't be notable in themselves.

  (See WP:LISTN.)

• List of notable items:

  The list topic need not be notable in itself.

  Nevertheless, each of the items should be notable.

  Various red-linked entries are acceptable if the entry is

  1. verifiably a member of the listed group, and
  2. likely to have an article on the topic in the future.

  (See WP:CSC.)

• Short, complete list:

  The list includes every item that is verifiably a member of the group.

  It is reasonably short.

  It could be useful or interesting to readers.

  Its inclusion of items is supported by reliable sources. Lists in which no entry is notable are rarely appropriate; see Wikipedia:CSC.

Refer to the relevant guidelines for further details.

Place one of the following templates at the bottom of the page, using the most specific template available. If there is no specific template, you can, as {{Set index article}} explains, use the most generic template with certain sort keys to more specifically categorize articles; the template's page also explains that you can use it to place pages into child categories of Category:Set index articles.

• {{Set index article}} for any set index article – Category:Set index articles

• {{Lake index}} for lakes - Category:Set index articles on lakes
• {{Mountain index}} for mountain names – Category:Set index articles on mountains
• {{River index}} for rivers – Category:Set index articles on rivers
• {{Road index}} for roads, streets, or highways – Category:Lists of roads sharing the same title

• {{Locomotive index}} for locomotives – Category:Set index articles on locomotives
• {{Ship index}} for ship names – Category:Set index articles on ships

For more information about set index articles for ships, see Wikipedia:WikiProject Ships/Guidelines § Index pages.

• {{Sport index}} for sport names – Category:Set index articles on sports
• {{Storm index}} for named storms - Category:Set index articles on storms
• {{Surname}} for people's surnames – Category:Surnames
• {{Given name}} for people's given names – Category:Given names
• {{Animal common name}} – Category:Set index articles on animal common names
• {{Plant common name}} – Category:Set index articles on plant common names
• {{Molecular formula index}} – Category:Set index articles on molecular formulas
• {{Chemistry index}} for chemical species – Category:Set index articles on chemistry

A summary of related policies and guidelines is given below. Editors should ensure that any set index article is compatible with these policies and guidelines. Refer to the current versions of the policies and guidelines for details.

• Wikipedia:History of SIAs
• Wikipedia:Broad-concept article
• Wikipedia:Lists
• Wikipedia:Outlines
• Wikipedia:Stand-alone lists