Background: Parenting styles mediate parental stress and child emotions in families of typically developing (TD) children. Our main aim was to study these relations in families of children with Down syndrome (DS), who in past research reported increased parental stress and permissive parenting. Method: Our sample included 100 parents of children with DS and 72 parents of TD children age 4-12 years. Parents completed online surveys of parental adjustment and emotion regulation (ER), parenting styles, and child ER and mood. Results: Parents of children with DS reported more distress and permissive parenting than parents of TD children. Within parents of children with DS, there was an indirect effect of parental stress on child emotions through permissive parenting. This effect was partly conditional upon parental ER and positive adjustment. Conclusions: Results have implications for distressed parents of children with DS whose families may benefit from improved coping strategies and increased support.