Background: Knowledge of the Adult Baby-Diaper Lovers (ABDL) phenomena is quite recent and there are, of yet, few studies on this phenomenon. Aim: This study was conceived to investigate the functions of ABDL behaviours and the characteristics of ABDL in an online Italian community sample. We hypothesized that ABDL phenomena were associated with general psychological maladjustment and with an experience of parental rejection during childhood. It was also assumed that there would be differences in ABDL profiles based on the age of appearance of their first Adult Baby-Diaper Lover (ABDL) fantasies. Method: An internet-based study was conducted and it involved 38 adults aged between 18 and 74 years (M = 34.95; SD = 12.25). Participants were first given an ad hoc questionnaire, which was devised to obtain information about the anamnestic variables related to ABDL. Then, the participants filled out the Cognitive Behaviour Assessment 2.0 battery to obtain anamnestic information regarding their psychological, medical, and personal history and to evaluate primary psychological dimensions in clinical practice. Finally, they filled out the Adult Parental Acceptance–Rejection Questionnaire, to evaluate their recollections of parental perceived rejection, and the Personality Assessment Questionnaire, to evaluate the primary psychological aspects related to parental rejection. Results: The data indicated that adults with ABDL showed the presence of anxious traits and recollections of parental rejection during childhood. Moreover, associations were observed between current or previous ABDL phenomena enuresis and negative mood states. Conclusion: Specific kinds of parental modes, anxiety traits, and enuresis seem to be the source of ABDL interests. Moreover, ADBL behaviours seem to assume different functions and meanings.