Coparenting the way partners work together in child-rearing-has been linked to long-term couple outcomes such as marital quality 2 and child outcomes such as internalizing/externalizing adjustment, attachment security, and academic success. 3 Although some studies have reported moderate stability in coparenting quality across the early years after birth, 2 the intervals between assessments have typically been quite large. Coparenting quality may fluctuate however at more rapid time scales as families deal with the stresses of early parenthood. 9 Research has shown that inconsistency/instability in parenting and family relationships is linked to insecure attachment 10 and greater strain on individuals and couples. 11 Accordingly, short-term (daily and monthly) fluctuations in coparenting may also represent a risk for poor individual and family outcomes. To better understand the dynamic processes of coparenting and how these dynamics influence families and children, this work will (1) utilize a daily measure of coparenting in a new daily diary study (Daily Family Life Project, DFLP), (2) examine predictors of variability in coparenting quality at the daily level (DFLP) and the monthly level (data from Project SIESTA, R01- HD052809, a study of parents across the first two years of parenthood), and (3) examine family and child outcomes of both daily and monthly variability in coparenting quality. Findings have the potential to inform the design of interventions for families with young children and should further strengthen families.