Infantilism may refer to:

• Paraphilic infantilism, a paraphilia involving the desire to wear diapers and/or fantasies of a return to infancy
• Psychosexual infantilism, a concept in psychosexual development introduced by Sigmund Freud
• Infantilism (physiological disorder) obsolete use of the term for some developmental disorders and disabilities
• Infantilism, also known as infantile speech, a speech disorder in which early speech stages persist beyond the age they are normally expected to fade
• Hypothalamic infantilism-obesity, or sexual infantilism, synonyms for adiposogenital dystrophy