The present paper assesses (a) the predictive utility of expanding the normative component of the theory of planned behavior (TPB) to include a measure of descriptive norms, and (b) the moderating role of group identification on TPB-intention relations. In Study 1 (N= 48), male soccer fans read a vignette describing a potential confrontation with opposition fans. In Study 2 (N= 129), male field-hockey players read a vignette describing an aggressive act against an opponent to prevent a goal. The TPB was a strong predictor of intentions (R2s= .80 and .64). The addition of descriptive norms increased the amount of variance explained in both studies. Little evidence was found to support the moderating role of group identification on TPB-intention relations. The discussion focuses on the distinction between attitudinal and behavioral descriptive norms, the group as an external facilitating control factor, and the impact of individuals’ self- and social identities.