Objective: Parenting and parent-child relationships change dramatically during development. One unique feature of developmental changes in parenting-lability-is associated with adolescent problem behaviors, above and beyond the general level and developmental trends of parenting. This study investigated lability in parental warmth in childhood, its associations with early adolescent adjustment, as well as antecedents in kindergarten: socioeconomic status (SES), parental depressive symptoms, and child problem behaviors. Method: Using longitudinal data from a large and racially diverse sample (N = 710, 46% urban Black, 58% male), parents reported their warmth annually from kindergarten to grade 5, as well as child externalizing and internalizing problems in grade 7. Teachers rated child social competence in grade 6. Results: Lability accounted for the majority of the variance in the year-to-year changes in parental warmth. Greater lability was associated with more internalizing problems and lower social competence. There was little evidence of the influence of child problem behaviors and parental depressive symptoms on lability. However, parents from lower-SES families showed greater lability in their warmth. Furthermore, lability partly explained the effects of SES on social competence in boys but not in girls, whereas the indirect effects of SES on internalizing problems through lability were significant in girls but not in boys. Conclusions: The findings highlight lability in parental warmth as a unique feature of the developmental changes in parenting in childhood, with linkages to adjustment in early adolescence. Family-based interventions should emphasize consistent parenting and provide stress management and coping skills for parents in order to reduce lability.