An adult baby is an adult who enjoys ageplaying a baby, usually as a sexual fetish. There is some overlap to the related but not identical fetish of wearing diapers, which is why the two are known together as AB/DL (adult baby / diaper lover).
Adult babies usually require a play partner as their 'mommy' or 'daddy' (or another guardian figure such as a nanny, governess or babysitter). The 'baby' role is, naturally, usually more of a passive role, while the 'guardian' role is more active.
Common practices include wearing baby-style clothing (such as onesies or footed pajamas, baby bonnets), diapers, using pacifiers, baby bottles, baby toys, stuffed animals, speaking 'babytalk', getting bathed, getting diapers changed, cleaned, oiled, powdered, and put to bed for a nap. Other roleplay may include feeding, playtime, cuddling, but also, if "necessary", scolding for "naughty" behavior and, possibly, punishment (e.g. light spanking). Those who like medical play may also enjoy enacting the taking of "medicine", rectal temperature taking or enemas.
 Diaper discipline
Diaper discipline is a scenario in which a (supposed) older child or adult is regressed into a baby-state as punishment for misdemeanors - a form of punishment through humiliation. It is in some way related to petticoat punishment.
 Common fantasy elements
Force or coercion is sometimes present in AB/DL fantasies. This can range from the inclusion of S&M or B&D play into AB scenarios through to more specifically AB scenarios such as the Diaper Discipline, or Petticoat Punishment in which a supposed older child or adult is regressed into a baby-state as punishment for misdemeanors. This can sometimes form a validation activity, where the AB mitigates their guilt for having AB desires with the fact that they are only in nappies as a punishment.
AB/DLs may enjoy looking at pictures showing whom they want to be, as opposed to whom they want to be with. For example, a heterosexual male adult baby may enjoy looking at pictures of men in diapers: he may be imagining himself as the men in the diapers.
 Permanent regression
A common fantasy among adult babies involves a permanent return to a more infantile position. This is a special case of a desire to regress, common among adult babies. This may involve being put back in diapers or returned to the nursery for the rest of their life. These fantasies may be enjoyed even by ABs who are consciously aware that they would not want to give up their adult lives.
Modesty and self-consciousness are not expected from infants and small children. Babies can be out in public in just a diaper and t-shirt, and can have their diaper changed in public. There are no local, state, or national laws that prohibit adults from wearing diapers, t-shirts, diaper covers, or body suits (onesies). Nonetheless, an adult in an uncovered diaper can expect to be treated like any adult in uncovered underwear, although no citations to support this statement are offered here.
 No privacy
Just as a baby has no responsibilities, they also have no privacy. The inclusion of scenarios where the AB is not granted genital privacy and has no rights of complaint or choice of activity can provide a return to a baby-state and can allow deep immersion in the baby mindset. In this context the AB is usually not allowed to touch themselves, but may have their nappy changed, their body cleaned, their genitals examined, and even be internally examined or given enemas/suppositories etc. without any warning, choice of circumstances or control over who is present. Their right to control access to their genitals is completely disregarded.
 Sissy babies, cross-dressing
A sissy baby  is a male AB/DL who mixes gender play with infantilism. This cross-dressing might involve stereotypical or exaggerated "little girl" clothing, such as frilly panties or dresses. Sissies are not necessarily transsexual in that, while some might be expressing an alter ego that is a baby girl, they might not wish to be an adult woman at other times.
A separate group enjoys the masochistic demasculinization of being dressed as baby girl, analogous to non-AB/DL masochists who enjoy being cross-dressed by force.
 Integrating other interests
The individual AB/DL may have other interests that have become integrated with AB/DL. Sissys are one example. In turn, a babyfur has integrated infantilism and furry fandom. Sissys and babyfurs are among many groups resulting from the integration of side-interests with infantilism. The combinations can themselves be combined in countless ways. For example, there are sissy babyfurs.
 Adult babies in art
 See also
- Forever A Kid - Adult Baby clothing shop
- Cutest One Of All - play clothes for Adult Babies shop
- Adult Baby Furniture - custom made furniture shop
- Lovely & Lacy Little Girlie Dresses - shop
- Adult Baby Boutique - shop
- Babes In Diapers - Blog dedicated to beautiful women is diapers, featuring stories, pictures and video clips
- Asian F/F mommy/baby ageplay photo 1, photo 2, photo 3, photo 4, photo5, photo 6, photo 7