A 4-year demonstration Total Communication Project was implemented at three schools (an elementary, a middle, and a high school) serving hearing impaired students. The goal of the project was for the six participating teachers to become consistent in their role modeling of English and American Sign Language (ASL), through weekly inservice on ASL and guidance in its appropriate use. Although English was the primary language of the classroom, ASL was used as an intervention tool. The paper describes: (1) techniques used for identifying classroom situations that call for the use of ASL, (2) discourse situations that influence the use of different language codes in total communication classrooms, and (3) guidelines for code-switching between English and ASL. The paper reviews the limited research on the effectiveness of ASL as an instructional tool, notes policy considerations, and offers a theoretical framework which sees ASL as a means of increasing deaf students' comprehension of instructional information. A variety of related issues are briefly addressed including the combined expression of signs and speech, the use of two languages in the classroom, attitudes toward ASL intervention, the conceptual function of signs, and the role of fingerspelling in instruction. 43 references. (DB)