An empirical analysis of the effects of alternative income maintenance programs, The Survey of Economic Opportunity, was used to obtain estimates of the labor supply parameters required to assess the implications of these programs for hours of work of male family heads. Labor supply response to changes in the family heads' net wages and in family income, based on data from a national sample of 6,000 households, was estimated by measuring the differences in annual hours of labor supplied by workers with different wages and different levels of nonwage income. These estimates were used in a simulation of the costs, impact on incomes, and changes in work patterns that could result from an extension to the working poor of income maintenance programs incorporating negative income tax principles. (BH)