In this article, Maria Martiniello reports the findings of a study of the linguistic complexity of math word problems that were found to exhibit differential item functioning for English-language learners (ELLs) and non-ELLs taking the Massachusetts Comprehensive Assessment System (MCAS) fourth-grade math test. It builds on prior research showing that greater linguistic complexity increases the difficulty of English-language math items for ELLs compared to non-ELLs of equivalent math proficiency. Through textual analyses, Martiniello describes the linguistic features of some of the 2003 MCAS math word problems that posed disproportionate difficulty for ELLs. Martiniello also uses excerpts from children's think-aloud transcripts to illustrate the reading comprehension challenges these features pose to Spanish-speaking ELLs. Through both DIF statistics and the voices of children, the article scrutinizes the appropriateness of inferences about ELLs' math knowledge based on linguistically complex test items. (Contains 1 table, 11 figures, and 5 notes.)