Parenting practices, including the use of physical discipline, are shaped by multiple influences. Although much research focuses on how parent, child, and dyadic characteristics shape parenting practices, extra-familial resources may also play a role. This paper focuses on how children's experiences of child care during the preschool years may affect one aspect of parenting--discipline practices. Using a rich, nationally representative data set, we explore the correlation between children's participation in centre based care, Head Start, or other non-parental care arrangements and parents' use of physical discipline, and related phenomena, parents' experience of domestic violence and parenting stress. We conduct probit regressions of parents' use of physical discipline, and parents' experiences of domestic violence, on preschool child care experiences. For disadvantaged groups of children, who have higher risks of experiencing physical discipline and witnessing family violence, we find that Head Start participation is associated with an increase in the likelihood that parents say they never spank their children and reduction in reports of domestic violence. And, for children in two-parent families, Head Start is associated with an increase in the likelihood that parents say they never spank their children and the likelihood that they do not say they would resort to spanking in a hypothetical situation. However, we find no evidence that non-parental child care is associated with a lasting reduction in parenting stress. (Contains 8 tables and 9 notes.)