This study sought to determine effective instructional practices for hearing-impaired students in mainstreamed and special classes. It involved a survey of 63 secondary mathematics teachers (with an 87% response rate), teacher logs of assignments and class work, and live observations. The study found no main effect for type of classroom (mainstreamed or special), achievement level of the class, or for 10 classroom process variables (such as positive feedback, homework frequency, and degree of individualization.) There was no interaction effect for the type of placement and the level of achievement. There was an interaction between the type of placement and the process variables, but no interaction effect between process variables and achievement. It appeared that successful mainstream placement may be defined by a greater degree of oral presentation and less seatwork, while a successful special class may be defined by less teacher talk and more seatwork. It is concluded that effectiveness was not found to be identical in the two situations, but the specific differences could not be clearly established. (14 references) (JDD)