Negative emotionality is considered to be the core of the "difficult temperament" concept (J. E. Bates, 1989; R. L. Shiner, 1998). In this correlational study, the authors examined whether the relations between children's negative emotionality and problematic behavior (internalizing and externalizing) were partially mediated by parenting style (authoritative and authoritarian) in a community sample of 196 3-year-old children and their mothers. The authors assessed maternal perception of child negative emotionality using the Children's Behavior Questionnaire (M. K. Rothbart, S. A. Ahadi, K. L. Hershey, & P. Fisher, 2001) and assessed problematic child behavior by means of maternal report using the Child Behavior Checklist (T. M. Achenbach, 1992). The results showed that the relations between child negative emotionality and internalizing and externalizing behaviors were partially mediated by mothers' authoritative parenting style. Moreover, when the authors used confirmatory factor analysis to decontaminate possible overlap in item content between measures assessing temperament and problematic behavior, the association between negative emotionality and internalizing behavior was fully mediated by authoritative parenting.