Despite being among the fastest growing segments of the student population, English Language Learners (ELLs) have yet to attain the same academic success as their English-proficient peers, particularly in science. In an effort to support the pedagogical needs of this group, educators have been urged to adopt inquiry approaches to science instruction. Whereas inquiry instruction has been shown to improve science outcomes for non-ELLs, systematic evidence in support of its effectiveness with ELLs has yet to be established. The current meta-analysis summarizes the effect of inquiry instruction on the science achievement of ELLs in elementary school. Although an analysis of 26 articles confirmed that inquiry instruction produced significantly greater impacts on measures of science achievement for ELLs compared to direct instruction, there was still a differential learning effect suggesting greater efficacy for non-ELLs compared to ELLs. Contextual factors that moderate these effects are identified and discussed.