This proposed PAR-OO-119 (B-START) Award includes a plan to pilot a preliminary investigation toward the validation of the diagnosis of Reactive Attachment Disorder (RAD). Validation of child psychiatric disorders in general, and disorders in early childhood in particular, are few. This holds for RAD, although clinical experience suggests that serious disturbances, if not disorders, of attachment exist. The objectives of this study are to serve as a pilot project focused on determining the criterion and procedural validity for the diagnosis of Reactive Attachment Disorder (RAD), and the discriminant validity of RAD versus the Disruptive Behavior Disorders (DBD) of Attention-Deficit- Hyperactivity Disorder (ADHD). Oppositional-Defiant Disorder (ODD) and Conduct Disorder (CD) in children between the ages of 18 and 48 months. RAD is a disorder of early childhood associated with institutionalization, abuse, and neglect, and is associated with serious impairments in socio-emotional relatedness. Two index groups (Abuse/Neglect and Psychosocial At-Risk Group) and one Comparison Group will be included. The three groups will be assessed using clinical interviews of the mothers focusing on attachment and disruptive behaviors as well as social competence. Finally, an interactional assessment that focuses on attachment related behavior will be administered jointly to the mother and child. All interviews and interactions will be videotaped and coded by trained raters, Data will be analyzed to assess criterion, procedural, and discriminant validity of the diagnosis of Reactive Attachment Disorder.