Best practice guidelines for adolescents considering bariatric surgery recommend a preoperative mental health evaluation. However, only general information about these assessments appears in the literature, which makes consistency of administration challenging. This review proposes a specific empirically derived format for pre-surgical mental health evaluations and summarizes currently available data on the psychiatric functioning of adolescents seeking bariatric surgery. Studies of mental health evaluations for adults preparing for bariatric surgery are reviewed, as is the limited literature relevant to adolescent evaluations. A specific and detailed example of an evaluation (clinical interview, self-report questionnaires, cognitive assessment) used for younger patients at a major metropolitan hospital centre is presented, followed by data from an initial group of adolescents completing this evaluation. A total of 200 adolescents (n = 139 female; age: 14–18 years; body mass index: 35.4–83.3 kg m−2) are presented for bariatric surgery. A notable subset of adolescents reported current Axis I conditions (31.5%) and current mental health treatment (29.5%), but reports of current illicit drug use (1.5%) and regular alcohol use (0.5%) were relatively rare. Procedures for using the completed evaluation and post-surgery monitoring of psychosocial issues are discussed. Adolescents considering weight loss surgery should receive comprehensive pre-surgical mental health evaluations, but additional data are needed to develop specific recommendations for the use of these evaluations in post-operative care.