Little is known about the roles of the family, kin and non-kin support networks in determining the use of social services by the elderly. An examination of the role of the formal and informal support systems to explain social service utilization by black and white older adults used path analytic procedures to test an explanatory model of utilization for a national area probability sample of 2026 noninstitutionalized older persons. Predisposing variables (race, sex, education, age, morale, marital status), enabling variables (income, population size, access to public transportation, perceived availability, family aid, family contact, informal non-family network), need-for-care variables (perceived need for social services, self-rated health status), and the criterion variable of social welfare service utilization were examined. Need for service was the most important causal variable. One enabling factor, availability, had a direct effect on use. Findings indicated that informal family support was more important for black older adults than white older adults. Family aid was a supplementary rather than an alternative support system. Results suggest that racial and cultural differences must become important factors in the planning, designing, and delivery of social services for the elderly. (Author/NRB)