From The Encyclopedia of Unusual Sex Practices, by Brenda Love (New York: Barricade Books, 1992).
(Autonepiophilia — arousal from playing role of infant, Infantophilia — arousal from playing role of infant) Infantilism refers to people who prefer to remain children and who often have an aversion to their adult bodies, facial or genital hair, or wearing adult clothing. There are cases of sexual and non-sexual infantiles. Infantilism differs from anaclitism in that the former consists of people who want to regress or act out the role of a child and the latter is a fetish relating to objects or acts from childhood.
There are cases of adults who act out their desires alone and without a partner. They may dress as a young boy and sit at home all day looking at themselves in the mirror or they may take a break and go to a park and play innocuous games with children. Others keep their body hair shaved, dress in children's clothing, and photograph themselves. One man took extreme pleasure in checking into a hotel and urinating in bed during the night. Infantilism was popular enough among the general populace for Germans to participate in adult baby balls after Lent.
Other adults find willing partners and create a multitude of scenarios. An infantile scene can last for many hours and the length is negotiated ahead of time because of this. The responsibility placed on the parent of a demanding infant can be very exhausting. The adult is not always a parent. He or she may be a young male child being baby-sat by a teenager who tucks them in, reads a bed time story, and tries to seduce the bashful but aroused young person. Scenes are also acted out where each partner dresses and plays the role of a child. Games of doctor and show me yours are also used.
Infantilism is on the increase because people are able, for a time, to have burdensome adult responsibilities taken away, and thus find it possible to "let go" emotionally (and perhaps sexually) in ways that would not be permitted the "adult." They are also allowed to demand nurturing and attention from their surrogate parent. They are now in total control and can have every whim fulfilled without feeling guilt. The act of getting by with things that they were punished for as a child creates a sense of empowerment and excitement. In addition to the emotional rejuvenation the child actor feels, a bond of trust and love is built between partners.
Infantilism can be therapeutic for people who are only able to accept unconditional nurturing by reverting to infancy or childhood. Others use this method to make up for the nurturing they didn't receive from their parents.
Infantilism does not always involve nurturing. It may be used in any S/M scene. Those trying to induce fear in a partner usually find it easier when the male is made to cross dress and to play the role of an innocent young girl.
Professional dominatrixes are often hired to act out adult roles for infantiles and there are magazines and clubs that provide information and paraphernalia. ("Alternate Personas," by Sybil Holiday and William Henkin, Ph.D., Society of Janus lecture, August 24, 1989)