This article describes the development and initial psychometric evaluation of an instrument to measure health-promoting life-style. Based on responses from 952 adults in midwestern communities, the Health-Promoting Lifestyle Profile was evaluated using item analysis, factor analysis, and reliability measures. Factor analysis isolated six dimensions: Self-Actualization, Health Responsibility, Exercise, Nutrition, Interpersonal Support, and Stress Management. These six factors accounted for 47.1% of the variance in the 48-item measure. Second-order factor analysis yielded a single factor, interpreted as Health-Promoting Lifestyle. The alpha reliability coefficient for the total scale is .922; alpha coefficients for the subscales range from .702 to .904. Further evaluation of the measure with different populations appears warranted. This instrument will enable researchers to investigate patterns and determinants of health-promoting life-style, as well as the effects of interventions to alter life-style.