This paper analyses the problems of treatment adherence in chronic pediatric diseases from a psychological point of view. We describe the repercussions of adherence on the course of the disease, the physician in charge, patients, and their relatives and place special emphasis on the complexity of the problem among adolescents. Factors impeding adherence are reviewed and factors related to disease and treatment, as well as cognitive, emotional, behavioral, familial, social, cultural, organizational and economic variables, are identified. The author proposes a psychological intervention that includes the assessment, prevention and management of problems of treatment adherence. The indications and implementation of each technique are outlined, distinguishing among educational, motivational and behavioral strategies. In summary, a psychological treatment program is proposed that may be easily applied to a large number of pediatric patients with chronic diseases and suspected or confirmed problems of treatment adherence.