The threat of unpredictable seizures makes epilepsy unique among childhood chronic illnesses. One consequence is that people who have childhood-onset epilepsy often have poor social adjustment and competence in adulthood. Better emotional and social functioning could improve long-term outcomes. Thirty-four adolescents with epilepsy participated in a group cognitive behavioral therapy program designed to enhance their level of psychosocial functioning. Baseline Strength and Difficulty Questionnaire scores suggested that many participants had difficulties with emotions, concentration, and social functioning, with parent-reported Impact scores significantly worse than adolescent-reported scores (p = 0.005). Four months after the intervention, adolescent-reported Prosocial Behavior scores significantly improved (p = 0.03). Parent-reported scores improved significantly at follow-up, compared with baseline, in Peer Problems (p = 0.04), Impact (p = 0.001), and Prosocial Behavior (p = 0.004) scores. Adolescents with lower socioeconomic status reported the greatest improvements (p = 0.01). A brief CBT intervention was effective and resulted in improved mental health indices and social functioning for adolescents with epilepsy.