Research in cognitive science has found that subjects regularly exhibit a conjunction fallacy in probability reasoning. Additionally, recent research has led to the finding of other fallacies in probability reasoning, including disjunction and conditional fallacies. Such analyzes of judgments are critical because of the substantial amount of probability judgment done in business organizational settings. However, in each case, the previous research has been conducted in the environment of a single decision maker. Since the business environment also employs groups, it is important to determine the impact of groups on such cognitive fallacies. This paper finds that groups substantially mitigate the impact of cognitive fallacies in probability reasoning among the sample of subjects investigated.