Background: Executive function (EF) plays a critical role in academic outcomes in typically developing children, but the contribution of EF to academic performance in Down syndrome (DS) is less well understood. This study evaluated differences in early academic foundations between primary school aged children with DS and non-verbal mental-age matched typically developing (TD) children. Additionally, the contribution of EF domains to academic outcomes was evaluated in each group. Method: Participants with DS (n = 29) and mental-age matched TD participants (n = 23) were administered the Woodcock Johnson-III NU Tests of Academic Achievement, as well as a laboratory-based EF battery, including measures of working memory, shifting, inhibition and object-planning. Results: Findings indicated a difference in early academic foundations profile between children with DS and mental-age matched TD children. Patterns of EF contributions towards academic outcomes were also observed across groups. Conclusions: Aspects of EF are critical to academic achievement in DS but differentially so relative to typical development. Implications for educational instruction are discussed.