Studies have shown that adversity in childhood has harmful effects on well-being across the lifespan. This study examined the prevalence of children's cumulative experiences of adversity, based on parent report, in a national sample of low-income children (N=3,208) enrolled in a high quality early childhood education (ece) program. It explored the association between family adversity that occurred within the year prior to the parents' interview and the child's well-being measured after the interview. Well-being was based on language, school readiness, and social emotional outcomes. Almost half of all families reported experiencing at least one adversity. Family adversity was associated with worse school readiness and health outcomes. Adversity had mixed associations with social-emotional outcomes and no association with language outcomes. This study also explored time enrolled in ece (dosage) as a protective or promotive factor in relation to adversity. Time in program had a positive relationship to most child outcomes and could be interpreted as a promotive factor within the context of adversity for all outcomes except behavioral concerns. (author abstract)