To determine the effects of oral sentence-structure exercises upon student writing, a 1-year experiment was conducted with two randomly matched fourth-grade classes of approximately equal size, one control class and one experimental class. The experimental group regularly completed exercises designed to teach students to produce sentences incorporating (1) "who" and "which" adjectival clauses or elements derived from these clauses, (2) adverbial clauses in initial and final position, and (3) nominalizations in the subject and predicate. Written exercises based on the oral drills were completed at the end of each class period. Before and after each of the two semester-long experimental phases, tests were administered in which students wrote a 30-minute impromptu composition about a short film. Results showed that students in the experimental group wrote more words in less time, used more of the practiced sentence structures, and used a greater proportion of complex sentences than did control group students. Consequently, the oral drills and supplementary written exercises were concluded to have favorably affected the writing of fourth graders. (Tables of findings are included.) (JM)