The primary aim of this study was to explore the relationship between teachers' instruction and students' vocabulary and comprehension in grades 3-5. The secondary aim of this study was to investigate whether this relationship differed for English monolingual and Spanish-English bilingual students. To meet these aims, we observed and recorded reading/language arts instruction in 33 classrooms at three points during an academic year, and we assessed 274 students on vocabulary and comprehension at the beginning and end of the year. Using field notes and student utterances to understand the context, we coded teacher utterances (e.g., questions, comments, prompts) as vocabulary instruction, comprehension instruction, other instruction, or noninstruction. We then identified five types of vocabulary-related instruction and five types of comprehension-related instruction. Using latent difference modeling, we investigated how the frequency of different types of instruction was associated with change in students' vocabulary and comprehension across the school year. Teachers' instruction related to definitions, word relations, and morphosyntax was positively associated with change in vocabulary; teachers' instruction related to application across contexts and literal comprehension was negatively associated with change in vocabulary; and teachers' instruction related to inferential comprehension was positively associated with change in comprehension. The findings also revealed an interaction between language status and teachers' instruction, such that instruction that attended to comprehension strategies was associated with greater positive change in comprehension for bilingual (but not for monolingual) students.