This study applied functional theory and media-capacity theory to compare face-to-face (FTF) groups with computer-mediated communication (CMC) groups in terms of their group communication and group performance. This study used a field experiment that was integrated into two classes of a communication course at a private university in northern Taiwan, in which 21 groups of 4 to 6 members worked on final group projects. The researchers randomly assigned one class, which had 11 groups (60 persons), to perform the task via CMC, and the other class, which had 10 groups (49 persons), to perform the task via FTF communication. The findings of this study in general support the functional theory and the media-capacity theory. However, some findings are not congruent with those of past studies. For example, previous studies have indicated that the function of criteria establishment was a significant predictor of group performance, while this study found this function to have no effect on the group outcomes. Furthermore, past studies found that the function of social talk had a negative effect on group performance, but this study discovered this function to have a positive effect on group outcomes.