The model makes a distinction between "voluntary" and "involuntary" welfare receipt. The findings suggest that, among female heads of households, the increase in welfare receipt that occurred between 1967 and 1979 was almost completely attributable to an increase in involuntary unemployment and an increase in the proportion of the population that was eligible for welfare (due to changes in program parameters). The passage of time, used as a proxy for changes in the stigma associated with receiving welfare, appears to be of secondary importance. The labor supply response to welfare programs is small and possibly diminishing over time. Copyright 1990 by Oxford University Press.