A study investigated whether syntactic differences between oral and written discourse interfere with the comprehension of beginning readers. Subjects were 28 second grade and 28 fifth grade students who read, orally, versions of stories identical in nature except for the structure of their syntactic patterns. One version contained structures more frequently found in written discourse (subordinate and relative clauses, appositive and participial phrases, and passive verbs), while the other used syntactic patterns more typical of oral discourse (coordinated clauses and active verbs). Reading comprehension was assessed with a standardized retelling task, and a measure of student familiarity with the syntactic patterns of written discourse was obtained with an oral storytelling task. Data analysis indicated that versions of stories with written discourse structures were marginally more difficult for students to comprehend than versions with oral structures, with the interference effect caused by written discourse structures being greater among second grade than among fifth grade students. Additional findings indicated that (1) the interference effect was significantly related to familiarity with these structures at the second but not the fifth grade level, and (2) students' word recognition errors reflected high expectations for syntactic patterns more typically found in oral discourse, especially among second grade students. (Two versions of a story used in the study are appended.) (FL)