We use data from the Fragile Families and Child Wellbeing Study to examine couple how couple relationship quality and parental engagement are linked over children's early years. Our sample includes 1,630 couples that are co-resident over years 1 to 3 and 1,376 over years 3 to 5 (1,196 over both periods). Overall, we find that better relationship quality predicts greater parental engagement for both mothers and fathers—especially from children's infant to toddler years; we find little evidence that parenting predicts future relationship quality. Married and cohabiting couples are generally similar in how relationship quality and parenting are linked. When couples are having their first birth, relationship quality is more strongly tied to parental engagement for fathers (but not mothers).