The ability to understand sentences contributes to students' reading comprehension. However, many reading programs tend to underemphasize explicit instruction aimed at enhancing students' knowledge of sentence structures. Children with language impairments, students with learning disabilities, and English language learners may particularly benefit from instruction that targets potentially challenging sentence structures. This article is designed to help educators and clinicians more effectively identify and teach several sentence structures that can compromise elementary and middle school students' understanding of written text. Four types of sentence structures that may be difficult to process are introduced and systematically explored: (a) sentences with passive verb constructions, (b) adverbial clauses with temporal and causal conjunctions, (c) center-embedded relative clauses, and (d) sentences with three or more clauses. Information is presented on syntactic structures, sources of confusion, developmental considerations, assessment caveats, and instructional strategies.