The five chapters of this report describe the development of a descriptive model of writing instruction in grades three through six. Data reported came from a study that included observations of 160 classes of writing instruction in eight classrooms throughout one school year. Following the first two chapters, which offer an overview of the study and its design, the remaining chapters describe (1) the constraints on writing instruction by forces outside the classroom, (2) the components of the developed model and the patterns of teaching behavior that were derived by using it, and (3) the potential for using progressive coding of student and teacher activity during a writing lesson to design more effective writing instruction. Appendixes include observation schedules and writing assignments, a curriculum for writing instruction for grades three through six, an annotated bibliography of writing instruction in the elementary schools, and further details about study results and instrumentation. (AEA)