Although many studies estimate the effects of welfare benefits on mothers' living arrangements, housing subsidies and prices are rarely the focus. This article uses a new longitudinal birth cohort study, the Fragile Families and Child Wellbeing Study, to examine the relationship between subsidized housing, housing prices, and the living arrangements of unmarried mothers three years after a nonmarital birth. Results suggest that the availability of subsidized housing is negatively associated with marriage relative to living alone. Eligibility criteria and means testing in subsidized housing may make marriage a costly choice. Housing prices are positively associated with marriage, cohabitation, and living with family members relative to living alone. Economies of scale may be particularly important for single-earner households when housing prices increase. Failure to control for housing costs and subsidies leads to underestimates of the effects of welfare and unemployment rates on the living arrangements of unmarried mothers.