This study uses a sample of 2,139 resident biological fathers from the Fragile Families and Child Wellbeing surveys (baseline and 12-month follow-up), to examine whether paternal aggravation and stress in parenting is associated with father engagement and coparenting and whether this association differs by father's socioeconomic status. Results of Ordinary Least Squares regression models indicate that paternal aggravation and stress in parenting is significantly associated with lower levels of father engagement and with less supportive coparenting relationships (controlling for mothers' aggravation and stress in parenting). Findings also indicate a more negative association between paternal aggravation/stress in parenting and father engagement and coparenting for fathers with household incomes below the poverty threshold. Findings suggest that policies aimed at decreasing parenting stress may be especially beneficial to fathers living in poor families. (Contains 2 figures and 3 tables.)