In order to advance our understanding of the etiology of individual differences in child maladjustment (i.e., conduct and emotional problems), we tested hypotheses about the statistical interactions between child temperament and two aspects of the family environment: maternal negativity and positivity, and household chaos (e.g., crowding, noise, lack of routines). Mothers (n = 149) reported on their child’s effortful control, negative affect, surgency, and behavioral/emotional problems. The age range of the children was 3 to 7 years old and half of the sample was girls. Observers rated maternal negativity and positivity based on brief structured interaction tasks in the laboratory. Child temperament moderated the association between maternal negativity/positivity and child maladjustment. Maternal negativity and child problem behavior were associated only for those children who also were high in surgency or negative affectivity. Maternal positivity was associated with less child problem behavior for those high in surgency. Child effortful control interacted with both maternal negativity and chaos. Maternal negativity and child problem behavior were most strongly associated for children who were low in effortful control and living in chaotic homes. The results point to distinct transactions between child temperament and maternal negativity/positivity that depend in part on the dimensions of temperament and parenting behavior in question.