Investments in preschool programs for children from disadvantaged backgrounds have historically been supported by research showing that these programs help children build school readiness skills and narrow the income-achievement gap. However, results from recent studies of the links between preschool participation and increases in school readiness skills are more mixed. Significant variation in regular preschool attendance and the availability of high-quality early learning environments could help explain mixed findings on preschool effectiveness. Using data from a preschool expansion demonstration project, we explored associations between children's attendance rates, classroom quality, and neighborhood poverty and children's fall to spring gains in a set of important school readiness skill in executive functioning. Children (N = 197) lived in neighborhoods where 26% of households (range = 0-92%) lived below the poverty line and attended 48 classrooms in public and private settings. Attendance rates, including chronic absenteeism, were significantly associated with children's gains in executive functioning skills, but only when children attended high-quality classrooms. Results suggest that efforts to increase attendance rates may benefit children's executive functioning skills among children living in higher poverty neighborhoods the most when communities also invest in increasing preschool classroom quality. (author abstract)