Using the public use file of the Early Childhood Longitudinal Study, Kindergarten class of 2010–2011, this study is the first to examine the extent to which science achievement is distinct from math and reading in kindergarten, first, and second grade; and the utility of kindergarten language proficiency and executive functioning (EF) for predicting science achievement among multilingual (n = 1022) and English monolingual (n = 12,343) children at each grade level. The results demonstrate that science is separable from math and reading achievement, though highly correlated. The results also indicate that kindergarten language proficiency and EF support science achievement similarly across elementary school for both groups. These results coupled with large correlations among science, math, and reading achievement suggest that integrated instruction that takes advantage of domain interconnectedness may reduce redundancies and help children connect with science content. (author abstract)