A review of the literature and analyses from two national surveys of physician practices showed major shifts occurred in stimulant prescriptions over the 1989-1996 period. Prescriptions comprised 75 percent of all visits to physicians by children with ADHD. Related services, such as health counseling, increased 10-fold and diagnostic services increased 3-fold. The provision of psychotherapy, however, decreased from 40 percent of pediatric visits to only 25 percent in the same time frame. Follow-up care also decreased from more than 90 percent of visits to only 75 percent. Family practitioners were more likely than either pediatricians or psychiatrists to prescribe stimulants and were less likely to use diagnostic services, provide mental health counseling, or recommend follow-up care. About 50 percent of children with identified ADHD who were seen in real-world practice settings received care that corresponded to guidelines of the American Academy of Child and Adolescent Psychiatry. Physicians reported significant barriers to service provision for these children, including lack of pediatric specialists, insurance obstacles, and lengthy waiting lists. The authors conclude that trends in ADHD treatment services and physician variations in service delivery point to major gaps between research and clinical practice. Clinical variations may reflect training differences, unevenness in the availability of specialists and the location of services, and changes in health care incentives. 45 references and 4 tables