This paper examines the effects of stronger child support enforcement and declines in welfare benefits on changes in non-marital childbearing between 1980 and 1996. Economic theory suggests that stricter child support enforcement will increase the costs of children for unwed fathers, making them less likely to have a child outside marriage. Reductions in welfare benefits also are expected to increase the costs of non-marital childbearing for both mothers and fathers. We examine these hypotheses, using aggregate state-level data and fixed effects regression models to identify the effects of policies on non-marital birth rates. We find that both stricter child support enforcement and declines in welfare benefits deter non-marital births. However, the estimated effects of child support enforcement are more robust and larger than those of welfare. The estimates imply that in the 1980-1996 period, increases in child support enforcement led to a decline in non-marital birth rates in the range of 6% to 9%, whereas decreases in welfare benefits led to a decline in the range of 2% to 4%.