This paper uses data from the 1970, 1980 and 1990 Censuses to investigate the impact of welfare benefits across Metropolitan Statistical Areas (MSAs) on the incidence of single motherhood and headship for young women. A contribution of the paper is the inclusion of both MSA fixed effects and MSA-specific time trends to account for fixed and trending unmeasured factors that could influence both welfare benefit levels and family formation. In such a model, we find no effect of welfare benefits on single motherhood for whites or blacks, and a positive effect of welfare benefits on single headship only for blacks.