Recent work examining science test performance in the earliest grades of school has demonstrated that science test score gaps by race/ethnicity are apparent as early as kindergarten and that, in a number of cases, the racial/ethnic test score gaps in science are significantly larger than the corresponding gaps in reading or mathematics. This study explores the factors that explain the differences in the magnitudes of racial/ethnic disparities in performance on science standardized tests as compared to those in reading/mathematics. Drawing on nationally representative data from over 10,000 kindergartners in the 2010-2011 school year, this study employs regression models that examine the explanatory power of nine conceptual domains for explaining the "gap-in-gaps" or test score gap differences in science relative to mathematics or reading. Results indicate that the gap-in-gaps is relatively unchanged by the inclusion of many conceptual domains but that students' language and immigration contexts do explain substantial portions of the gap-in-gaps for Hispanic and Asian students. Implications for policy and practice are discussed.