Economic stress been shown to compromise children’s social development and undermine parenting behaviors in mothers of young children. A separate literature suggests that social support may attenuate the negative effects of maternal stress on parenting behaviors. Guided by the Family Stress Model and the Stress Buffering Model, this study examined the indirect pathways from maternal experiences of stress (economic and parenting) to children’s social competencies and behavior problems longitudinally in a sample of children from the Early Head Start Family and Child Experiences Survey (Baby FACES). It also tested the moderating effects of two types of social support (instrumental and emotional) on the negative association between stressors (economic and parenting) and children’s social skills. Using structural equation modeling (SEM) results demonstrated support for the Family Stress Model, such that economic stress (at age 1) was longitudinally and indirectly related to children’s social competencies and problem behaviors (at age 3) via observed maternal sensitivity (at age 2). That is, higher levels of economic stress were related to elevated levels of behavior problems and lower levels of social competencies because it increased parenting stress and decreased maternal sensitivity. However, there was no evidence that social support moderated the association between either type of stress and parenting. Findings are discussed in light of policy and programmatic efforts to broaden support of families and children by incorporating services that promote sensitive parent-child interactions and reduce maternal parenting stress.