The present study sought to further specify conceptual models of youth positive affect (PA) by examining mothers’ observed PA as a mediator of the relation between family risk (based on maternal reports of demographic factors) and children’s PA in a sample of 82 mothers (M = 31.25 years, SD = 6.16) and their preschool-aged children (M = 3.51 years, SD = .49, 63.00 % boys). Results yielded a significant, negative correlation between family risk and child PA. Mediation analyses indicated that family risk was related to child PA through its effects on maternal PA, even after controlling for maternal depression symptoms. Findings suggest that family risk and maternal PA are important factors to consider in understanding preschoolers’ PA development. Identifying children at risk for developing PA difficulties can aid in the implementation of prevention and intervention strategies for promoting young children’s PA specifically, and their psychosocial functioning more broadly.