This paper describes the development and preliminary validation of the Multidimensional Health Profile-Health Functioning Index (MHP-H), a 69-item self-report instrument designed to assess a variety of behaviors, perceptions, attitudes, and beliefs presumed to influence health status and the pursuit of lay and professional health care. The MHP-H briefly measures adult health history, health habits, health care utilization, health beliefs and attitudes, and response to illness (help-seeking behaviors). A national sample of adults (N = 673) was assessed, comprising 3 age groupings (18-32, 33-50, and 51-89) crossed with gender and then further subdivided into several subsamples for purposes of reliability and validity assessment. In addition, a group of spouse "key informants" was also recruited. Preliminary validation of single-item indicators as well as confirmatory factor analyses of multi-item scales was achieved. The present findings support the psychometric and practical utility of the MHP-H and warrant its use by health psychologists in a variety of research and applied settings.