Early childhood care and education (ECCE) programs are an important mechanism for supporting foundational skill development and successful progression through later schooling. School readiness assessments that serve as reliable indicators of children's later educational outcomes are most useful for education systems, but little is known about how well-existing assessments predict primary school performance in low- and middle-income countries. This study uses longitudinal data from Ghana to investigate how the International Development and Early Learning Assessment (IDELA) predicts future reading and math skills as measured by the Early Grade Reading Assessment (EGRA) and Early Grade Mathematics Assessment (EGMA). Results demonstrate significant and meaningful associations between IDELA scores in ECCE and early primary school academic skills. We find that all domains of development measured by IDELA (i.e., Emergent Literacy, Emergent Numeracy, Motor Development, and Social-emotional Development) are predictive of later academic performance, and that the domains of Emergent Literacy and Emergent Numeracy are the strongest predictors of EGRA and EGMA. Our findings indicate that it is feasible to monitor children's school readiness with strong predictive validity across several years of schooling, and points to several promising avenues for future research for education monitoring systems across the region.