This article reports four case studies illustrating the implementation of the Choose Health Program, a cognitive behavioural lifestyle intervention for overweight and obese adolescents. Participants were an overweight (12 years) and obese (15 years) female, and an overweight (14 years) and obese (12 years) male. The program was delivered by provisional psychologists with program specific training and supervision. All participants demonstrated improvements in body composition, and maintained or improved dietary quality and psychosocial wellbeing. The program had variable effects on physical activity and minimal effect on cardiovascular fitness for three of the four participants. While parents and adolescents required considerable assistance to develop and monitor long term program goals, these goals were a useful clinical tool to support the adolescent and parent to recognise the improvements they had made. Identification and monitoring of specific, measurable, and realistic behaviour change strategies was particularly important in assisting adolescents and their parents to translate session information into improved health behaviours. Results indicate that an adolescent overweight and obesity treatment program that promotes adolescent responsibility and autonomy, and emphasises the importance of parent support and family change is both effective and highly acceptable to both adolescents and parents.