Four studies by the Cognitive Strategy Instruction in Writing project at the Institute for Research on Teaching, Michigan State University, examined the acquisition of expository writing skills in fifth and sixth grade students. The first study examined the effects of teaching sixth grade students about comparison/contrast text structure. Results indicated that such instruction improved sixth grade students' text recall, summary organization, and appropriate use of key words and phrases. The second study (in which eight teachers and their students participated) introduced fifth and sixth grade students to the writing process with emphasis on: (1) audience and purpose; (2) the role of text structure knowledge in planning, drafting, and revising; and (3) audience, purpose, and text structure knowledge. This study presented students with "think-sheets" to prompt students through the writing process, and results indicated that students in these programs made significant gains in their free writing skills. The third study reported on the participation of an experienced fifth grade teacher in the previous studies, and noted that the teacher internalized the teaching strategies presented in the program. Finally, the fourth study involved an extensive descriptive examination of the writing curriculum used in special education classrooms and with special education students mainstreamed into regular classrooms. Based on the results of these studies, a revised expository writing program was developed. (Samples of students' writings and one figure are included, and sample planning, organizing, editing, and revising work sheets, one footnote and 49 references are appended.) (MM)