To evaluate whether conjoined maternal posttraumatic stress disorder (PTSD) and depression are associated with increased behavioral problems among terrorism-exposed preschool children (N = 116; 18–54 months), this study compared clinically significant child behavioral problem rates among the preschool children of mothers with PTSD and depression, depression alone, and neither disorder. Behavioral problems were independently rated by mothers and preschool teachers. Maternal depression and PTSD, relative to maternal depression alone, and to neither disorder, were associated with substantially increased child problems. Notably, maternal depression and PTSD were associated with increased emotional reactivity (relative risk [RR] = 5.9 by mother’s and 3.4 by teacher’s reports) and aggressive behavior problems (RR = 11.0 by mother’s and RR = 5.9 by teacher’s reports). This was corroborated by teacher ratings. Implications for intervening with terrorism-exposed preschool children are discussed.