Thinking through Writing (TTW) was a project to develop, test, and disseminate a program for teaching thinking and writing skills in secondary school English and social studies courses. Each of the 12 schools participating in the project scheduled a group of students to take an English and a social studies course in the program, and two teachers from each school participated as a team to develop parallel courses and materials, test them in their classrooms, and provide feedback. The four major objectives in the TTW project were to (1) develop a text-workbook, (2) develop a teacher's guide, (3) design methods for using the program across the curriculum, and (4) design writing assignments for these courses to improve students' thinking and writing in the content areas. The one-year evaluation of the text-workbook, teacher's guide, methods, and writing assignments was designed to determine the effectiveness of the program by means of a pre- and postwriting sample and informal methods to evaluate the improvement in students' thinking skills. The findings indicated that the program improved students' writing ability and critical reading. The evaluation showed that the program functioned well with average students in grades 9 through 12 and that above average students were appropriately challenged by the problem solving approach. (A list of participating schools is appended.) (HTH)