Research has demonstrated that the presence of others shifts decision‐making about risky/deviant behavior. One reason for this shift could be changes in the anticipated experience of formal sanctions, informal costs, and rewards. To investigate this possibility, this study conducted two randomized controlled trials with hypothetical vignettes, in which a range of how many other people were also involved in the criminal act defined the treatment conditions. Across two samples of university students (Ns = 396 and 263), the results revealed that as the size of the involved group increased, the anticipated experience of sanction risk and several informal social costs associated with engaging in the act decreased, and the anticipated experience of two rewards increased. Additional analyses suggest that, with one exception in each data set, these changes are not only tied to the solo/group distinction.