Most of what is known about the association between children's executive function (EF) and school readiness skills is derived from research conducted in Western countries. We tested whether these associations were evident in a middle-income country context. Participants were 1,480 children, aged 4-7 years old, who participated in an endline assessment of the Tayari program, an early childhood education (ECE) model that is being delivered by the Kenyan education system. High rates of task completion, low rates of floor effects, and high rates of assessor quality ratings supported the feasibility of large-scale direct assessments of EF with young children. Assessor ratings of children's attention-related behaviors during testing were positively associated with their performance on EF tasks (rs = 0.12-0.27). An EF composite score was not related to demographic factors or to children's exposure to the Tayari program. However, the EF composite score was uniquely associated with performance-based measures of early literacy ([beta] = 0.18, 95% confidence interval [CI] = 0.05, 0.31), early numeracy ([beta] = 0.16, 95% CI = 0.07, 26), and social-emotional competencies ([beta] = 0.12, 95% CI = 0.03, 0.20), even after adjustment for multiple covariates. These results are discussed with respect to the ways in which EF skills inform ongoing efforts to invest in ECE in low- and middle-income countries.