The transition process from pediatric to adult health care for adolescents with chronic diseases is always challenging and can be even more so for adolescents with HIV disease. The purpose of this study was to describe characteristics and current practices surrounding the transition of adolescents from the clinics of the Adolescent Trials Network for HIV/AIDS Interventions to adult medical care. This report focuses on the processes of transition, perceived barriers and facilitators, and anecdotal reports of successes and failures. Practice models used to assist adolescents during transition to adult medical care are described. Interviews were conducted with 19 key informants from 14 Adolescent Trials Network clinics. Findings revealed no consistent definition of “successful” transition, little consensus among the sites regarding specific elements of a transition program, and a lack of mechanisms to assess outcomes. Sites that viewed transition as a process rather than an event consistently described more structured program elements.