Group polarization is the tendency of people to become more extreme in their thinking following group discussion. It may be beneficial to some, but detrimental to other, organizational decisions. This study examines how computer-mediated communication (CMC) may be associated with group polarization. Two laboratory experiments were carried out. The first experiment, conducted in an identified setting, demonstrated that removal of verbal cues might not have reduced social presence sufficiently to impact group polarization, but removal of visual cues might have reduced social presence sufficiently to raise group polarization. Besides confirming the results of the first experiment, the second experiment showed that the provision of anonymity might also have reduced social presence sufficiently to raise group polarization. Analyses of process data from both experiments indicated that the reduction in social presence might have increased group polarization by causing people to generate more novel arguments and engage in more one-upmanship behavior. Collectively, process and outcome data from both experiments reveal how group polarization might be affected by level of social presence. Specifically, group discussion carried out in an unsupported setting or an identified face-to-face CMC setting tends to result in weaker group polarization. Conversely, group discussion conducted in an anonymous face-to-face CMC setting or a dispersed CMC setting (with or without anonymity) tends to lead to stronger group polarization. Implications of these results for further research and practice are provided.