This is the fourth and final report in a series dealing with the impact of the modes of discourse (description, narration, exposition, and argumentation) on written syntactic complexity at the elementary school level. The first three reports dealt in turn with the three grade levels involved in the study (third, fourth, and fifth grades). This report summarizes grade-level findings and investigates across-grade differences between the 153 writers involved. The findings indicate that writers at these grade levels are influenced to a significant degree by the mode of discourse invoked by their writing assignment: different modes invoke different syntactic resources, reflected in such measures as T-unit length, clause length, and clauses per T-unit. (AA)