This chapter seeks to assess contributions of behavioral scientists to our understanding of sociocultural and psychological factors as these relate to health care utilization. Relevant research and theory will be critically reviewed with a focus on areas of current research interest. Research has shown large differences in the patterns of health care utilization across countries and within regions. Rates of hospitalization in some countries are over twice as high as what they are in others and rates of physician visits are several times higher in certain countries or regions of countries than in others. The variety of types of care must be recognized in health care utilization research. A number of available "models" of utilization of physician services are built on the notion of stages or decision points. Health care utilization researchers need to fully recognize that income related inequities still exist for certain populations and that those inequities may persist due to other non-financial social and psychological reasons.