Using the Early Childhood Longitudinal Study Kindergarten Cohort (2010-2011), this study is the first to investigate predictors of kindergarten science achievement and growth across elementary school--English language proficiency (ELP), executive functioning, math and reading achievement, parent-engaged science and math activities, and classroom science content coverage--separately for multilinguals (n = 1,023) and English monolinguals (n = 12,329). Multigroup latent growth curve models indicate initial differences in science are largely explained by the group of predictors, multilinguals learn science more rapidly in early elementary school than English monolinguals, and science scores are not meaningfully different between the fifth-grade groups. Among other notable results, ELP predicts science growth for both groups and math achievement predicts science growth for multilinguals only; reading achievement only predicts growth for English monolinguals. The findings from this study strongly challenge the prevailing belief that being multilingual in the United States leads to poor achievement.