Despite progress, ADHD and its treatment have remained controversial, especially the use of psychostimulants for both short-term and long-term treatment. Although an independent diagnostic test for ADHD does not exist, there is evidence to support the validity of the disorder. Studies, including randomized clinical trials, have established the efficacy of stimulants and psychosocial treatments for alleviating the symptoms of ADHD and associated aggressiveness and have indicated stimulants are more effective than psychosocial therapies in treating these symptoms. Because of the lack of consistent improvement beyond the core symptoms and the paucity of long-term studies, there is a need for more research into drugs and behavioral modalities and their combination. Although trials are underway, conclusive recommendations concerning treatment over the long-term cannot be made at present. There are wide variations in the use of psychostimulants across communities and physicians, suggesting no consensus regarding which ADHD patients should be treated with psychostimulants and the need for improved assessment, treatment, and follow-up. Further, lack of insurance coverage prevents the appropriate diagnosis and treatment of ADHD. After years of clinical research and experience with ADHD, knowledge about its causes remain largely speculative, and there are no documented strategies to prevent ADHD. 108 references