National health surveys have played an important role in the development of health services research. They have contributed to the advancement of concepts, methods, and the policy relevance of the field. One product of these surveys was the Behavioral Model of Health Services Use. This article documents a 75-year legacy by reviewing the series of national studies that have given to the form and function of health services research. It further examines the Behavioral Model through 40 years of considerable application and alteration.