The present study used a unique design in which multiple factors were combined in a multiphase study to find if there are any significant interactions among six factors known to be effective in successful group work. The results indicated that the effectiveness of group work depends on how the effectiveness is measured, how the group is formed, and what type of task is assigned to learners. An interaction of six major factors including mode of instruction (face-to-face vs online), type of task (convergent vs divergent), anonymity of participants, homogeneity of students in terms of their skill level, utilization of peer assessment, and group size, was found to play a significant role in the effectiveness of group work.