Interest in the health care needs and medical care utilization patterns of older persons has steadily increased in recent years. The major goal of this study was to examine the extent to which specific factors moderate the relationship between life stress exposure and subsequent health services utilization. Two groups of older persons (health maintenance organization members and fee-for-service clients) participating in a multiyear panel study comprised the study sample. Time-ordered, multivariate analyses of links among life stress exposure, moderating variables, and subsequent health services utilization indicate that the process may not be direct or simple to explain. There was no indication in this study that social support had any direct moderating effects on the time-ordered relationship between life stress exposure and the utilization of medical care services. However, the interaction of high life stress exposure and low social support was consistently linked to increased rates of health services utilization.