Youths with chronic physical illnesses face increased rates of psychological problems and the burden of coping with physical illness-related challenges. The following data describes treatment outcome maintenance results from a randomized clinical trial investigating the impact of a cognitive behavioral intervention Primary and Secondary Control Enhancement Therapy-Physical Illness (PASCET-PI) as compared to treatment as usual (TAU) on youths with inflammatory bowel disease (IBD). Forty-one participants aged 11-17 with IBD and concurrent depressive symptomatology were randomized to PASCET-PI (n = 22) or TAU (n = 19). Self-reported depressive features, global functioning, and DSM-IV depressive symptomatology were assessed immediately post-treatment (T2), followed by assessments at 6-months (T3) and 12-months (T4) post-treatment initiation. Repeated measure models revealed significantly improved global psychosocial functioning in youths randomized to PASCET-PI compared to youths randomized to TAU. Improvements in self-reported depressive features and DSM-IV depressive symptoms were found at the trend level for youths randomized to PASCET-PI relative to those receiving TAU. Effect size estimates for all outcome variables suggested large to medium treatment effects.