The final report of the project that concentrated on the expository language found in content-area textbooks begins with an overview of the project, including rationale, significance, and goals. These goals were to (1) describe how high school students and their teachers used their textbooks, (2) describe and analyze the nature of expository texts, (3) examine the influence of characteristics of expository texts upon different readers' memory for text, (4) determine the influence of various instructional procedures upon students' ability to learn from text, and (5) examine the influence of text manipulations upon the quality of students' learning from text. The remaining sections of the report address the secondary students' use of biology and history textbooks; describe the characteristics of texts, especially through their language; discuss text analytic procedures (validation and criticism); define reader characteristics; examine text-based instructional studies; and discuss text engineering. The summation of the project is provided in the final section. Appendixes include the surveys administered to students in Illinois and Texas; tables relevant to secondary students' use of biology and history textbooks; a complete set of texts, maps, and lists of relationship propositions; examples of scoring and rationale for scoring two free recall protocols; tables relevant to students; recall of text units; individual subjects' ratings of the ease of resolution and the importance of cohesive ties; graphs of predictability ratings of topic continuity; and the importance of rating sentences. (HOD)