Children can benefit from involved fathers and cooperative parents, a benefit which may be particularly important to the growing population of children born to unmarried parents. This study observes father involvement and coparenting in 5,407 married and unmarried cohabiting couples with a 2-year-old child in the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B). A link was found between cooperative coparenting and father involvement for all couples. Compared with married couples, couples who married in response to the pregnancy and couples who remained unmarried showed higher levels of father involvement and more cooperative coparenting, indicating a potentially greater child focus. (Contains 3 tables.)