Research documents that lability in parent-child relationships–fluctuations up and down in parent-child relationships–is normative during adolescence and is associated with increased risk for negative outcomes for youth. Yet little is known about factors that predict lability in parenting. This study evaluated whether children’s behaviors predicted lability in parent-child relationships. Specifically this study tested whether youth maladjustment (delinquency, substance use, internalizing problems) in Grade 6 was associated with greater lability (e.g., more fluctuations) in parents’ warmth and hostility towards their children across Grades 6–8. The study also tested whether the associations between youth maladjustment and lability in parents’ warmth and hostility were moderated by parents’ internalizing problems. The sample included youth and their parents in two parent families who resided in rural communities and small towns (N = 618; 52% girls, 90% Caucasian). Findings suggest that parents’ internalizing problems moderated the associations between child maladjustment and parenting lability. Among parents with high levels of internalizing problems, higher levels of youth maladjustment were associated with greater lability in parents’ warmth. Among parents with low in internalizing problems, higher levels of youth maladjustment were associated with less lability in parents’ warmth. The discussion focuses on how and why parent internalizing problems may affect parental reactivity to youth problem behavior and intervention implications.