A study was done to foster interest in Supplemental Instruction (SI), an instructional intervention which helps students develop study skills relevant to a particular course, and to investigate the effects of participation in an SI program for a first semester, college level mathematics course in business calculus. The course had a consistent grade distribution pattern in which at least 30 percent of the students received a grade of D or F or withdrew. The study used two lecture classes with the same instructor. Each class was divided into two discussion sections, and of those, one from each received the SI treatment. The preliminary group of subjects consisted of 84 students from the control discussion sections and 83 students from the treatment discussion sections. In the control sections the teaching assistant performed typical duties. In the SI sections the assistant performed the same duties but in addition she provided instruction on the study skills relevant to the course as it progressed. The results showed a statistically significant difference between the control group mean semester grade point average (GPA) of 2.51 and that for the treatment group GPA of 2.95, a result suggesting that students receiving SI treatment outperformed their control group counterparts. Included are 4 tables, 1 figure and 22 references. (JB)