Does state AFDC generosity affect child SSI participation?

This article examines the extent of interactions or spillovers between the Supple mental Security Income (SSI) and Aid to Families with Dependent Chil dren (AFDC) programs for children. In the early 1990s, the Social Security Administration substantially relaxed child eligibility criteria for SSI ben efits. Since the changes, the number of U.S. children receiving cash and me dical benefits through SSI tripled to nearly I million. The article describ es a family's decision to participate in SSI and/or AFDC, and uses state-le vel data for three venus before, and three years after the Zebley decision to estimate the effect of state program generosity on child program partici pation. The expansions in child SST eligibility increased child SSI partici pation aid contributed to increased total program participation by children in the early 1990s. Child SSI participation increased more in states with lower AFDC payments and higher state SSI supplementation payments. These re sults suggest that families use SSI and AFDC as substitutes. Ar least 32 pe rcent of the Zebley increase in SSI is likely attributable to the SSI-AFDC benefit gap for the median AFDC benefit state. (C) 2000 by the Association for Public Policy and Management.