Emotion regulation is a core developmental process that is related to children's academic success and mental health. A small body of research has documented that maltreated children show deficits in this developmental arena. The current study was designed to add to the limited literature on emotion regulation in maltreated children in foster care. Emotion regulation tasks were administered to preschool foster children, videotaped, and later coded. Parenting was assessed via coded observations of mother-child interactions. Mothers reported on their experience of depressive symptomatology. We examined the relation of foster parenting and foster mother depression, as well as child characteristics and child welfare experiences, to emotion regulation, specifically in the joy and anger domains. Findings revealed that maternal depression and parental structuring significantly contributed to children's anger regulation, but not to their regulation of joy. These findings are considered in the context of future research with respect to young maltreated children in foster care.