Electronic brainstorming (EBS) has been a focus of academic research since the 1980s. The results suggest that in most—but not all—cases, groups using EBS produce more ideas than groups using verbal brainstorming. In contrast, the results comparing groups using EBS to groups using nominal group brainstorming have been mixed: sometimes EBS group produce more ideas, while in other cases, nominal groups produce more. This article examines the effects of group size on EBS, verbal brainstorming, and nominal group brainstorming. We found that group size is a significant factor in predicting the performance of EBS relative to verbal brainstorming, and nominal group brainstorming. As group size increases, the relative benefit of EBS increases. EBS groups outperform verbal groups when group size reaches four people. EBS groups outperform nominal groups when group size reaches 10 people.