The newly-created National Center for Health Services Research and Development, as the focal point for research and development in the personal health services of the nation, has as one of its major objectives improvement in the precision with which health services can be evaluated. This effort, to the extent that it is successful, will permit better monitoring of ongoing programs and more valid experimentation with novel approaches to health care delivery. Initial efforts in evaluation will be concentrated on health care programs for the disadvantaged and on multiphasic screening. This initial approach is justified by the Center's concern with helping to solve pressing sociomedical problems and by the conviction that techniques developed in these efforts should have general applicability in improving the assessment of the impact of health services on populations.