Previous research provides evidence that individual differences in the personality characteristic of extraversion/introversion can play a significant role in group idea generation. Cognitive stimulation has also been shown to have a significant, though inconsistent, influence on idea generation in computer-mediated groups.We conducted two controlled experiments using a web-based group simulator to empirically test the impacts of these factors on group idea generation. In the first experiment, extraverts outperformed introverts in computer-mediated groups. In the second experiment, we exposed participants in computer-mediated groups to four levels of idea stimulation ranging from none to extremely high. Extraverts generated more unique and diverse ideas than did introverts in moderate- and high-stimuli conditions only. In sum, our study provides empirical evidence regarding the significant effect of individual differences, in this case the personality characteristic of extraversion/introversion on idea generation in a computer-mediated group. We have also demonstrated that a relationship exists between the level of cognitive stimulation and idea generation, with moderate levels of idea stimulation optimal for extraverts in computer-mediated groups. Theoretical and practical implications of these findings are discussed.