As more and more medical practice guidelines are developed in the United States, commensurate evaluation efforts should assess their impact on professional practice and patient outcomes. We describe an ongoing research program designed to develop and test practice models for applying the 1988 Adult Treatment Panel Guidelines for the clinical management of high blood cholesterol. Four studies are evaluating different models to assist nonacademic community practices in the detection, evaluation, and treatment of high blood cholesterol. We have designed randomized controlled trials set in solo and small-group primary care practices of family or general practitioners and internists situated in rural, suburban, and urban settings. Patients include adult men and women who represent diverse socioeconomic and ethnic backgrounds. We are measuring rates of cholesterol screening; dietary and drug treatment and follow-up; changes in dietary intake and compliance with drug therapy; changes in quality of life and cost of intervention; and reduction in cholesterol level. Scheduled for completion in 1994, this program will provide insights into practical and effective methods of lipid management. It serves as a model for studying the application of health guidelines in the context of nonacademic primary care practices serving diverse patient populations.