This paper examines temporal changes in staffing ratios and configuration of mental health providers per 100,000 members within two full-service staff-model health maintenance organizations (HMOs). Overall workforce reductions in all classes of mental health professionals occurred in the two HMOs from 1992 to 1995. Staffing ratios decreased in both HMOs for psychiatrists and psychologists. In one HMO, the ratio of clinical social workers also decreased over this period. Provider ratios from 1995 are benchmarked against state ratios per 100,000 population. Workforce mix for the two HMOs is contrasted with a single-year average for a large managed behavioral health (carve-out) organization. The authors discuss potential implications of the findings for training of several categories of mental health professionals.