English language learners (ELLs) and their teachers, schools, and communities face increasingly high-stakes consequences due to test score gaps between ELLs and non-ELLs. It is essential that the field of educational assessment continue to investigate the meaning of these test score gaps. This article discusses the findings of an exploratory study of the response processes of grade 5 ELLs and non-ELLs on multiple-choice science test items from a high-stakes test. We found that the ELL students in our sample were more likely than the non-ELL students to answer incorrectly despite demonstrating knowledge of the science content targeted by the test items. Investigating the interview transcripts of ELL students who answered in this way revealed that ELL students' interactions with specific linguistic features of test items often led to alternative interpretations of the items that resulted in incorrect answers. The implications of this work for the assessment of ELLs in science are discussed.