This study uses data from 2,309 biological fathers who participated in the Fragile Families and Child Well-Being Study (FFCWS) to examine associations between psychosocial characteristics and levels of corporal punishment (CP) toward their 3-year-old children over the past month. Results indicate that 61% of the fathers reported no CP over the past month, 23% reported using CP once or twice, and 16% reported using CP a few times in the past month or more. In multivariate models controlling for important sociodemographic factors as well as characteristics of the child, fathers' parenting stress, major depression, heavy alcohol use, and drug use were significantly associated with greater use of CP, whereas involvement with the child and generalized anxiety disorder were not. Girls were less likely to be the recipient of CP than were boys, and child externalizing behavior problems but not internalizing behavior problems were associated with more CP. (Contains 2 tables.)