A modified multiple baseline across behaviors design was used to evaluate the effects of an interdependent group contingency program with randomly selected contingency components on the academic performance of an intact middle-school class serving five male students with serious emotional disturbance (SED). During the initial intervention phase, students had to meet a randomly selected criterion (e.g., 80% or 90% class average) on daily spelling assignments to earn a randomly selected group reward. Mathematics and then English daily assignment performance were added to the program in subsequent phases, and target assignments (i.e., either spelling, mathematics, or English) and criterion were randomly selected. Results show educationally valid increases in academic performance as target assignments were added to the program. (Contains 1 figure and 1 table.)