This article assesses the effectiveness of in-hospital paternity establishment, a federal requirement since 1993. We avoid biases in previous studies by using a national sample of nonmarital births (N= 3,254), by including detailed controls for characteristics of unwed mothers and previously unavailable controls for characteristics of fathers, and by estimating reduced form models of the effects of strong paternity establishment regimes. We find that paternity establishment rates are now quite high—69%—and that 6 of 7 paternities are established in the hospital. Even after controlling for previously unavailable characteristics, establishing paternity (in and outside the hospital) is significantly and positively associated with formal and informal child support payments and father-child visitation. These results hold up in the reduced form models.