Background: The current studies aim to show that descriptive social norms influence vegetable intake and to investigate three potentially underlying processes (self‐identification, attitude, and self‐efficacy). Methods: In two studies, descriptive social norms regarding vegetable intake were manipulated (majority vs. minority norm). Study 1 investigated both the relation between baseline vegetable intake and self‐identification, attitude, and self‐efficacy, as well as the effect of the norm manipulation on vegetable intake over a one‐week period. Study 2 investigated potential mediation of the effect of the manipulation on vegetable intake intentions through self‐identification, attitude, and self‐efficacy. Results: Study 1 showed that the proposed mediators were related to a baseline measure of vegetable intake. Moreover, in participants identifying strongly with the norm referent group, majority norms led to higher vegetable consumption than minority norms. Study 2 showed that the direct effect of the social norm manipulation on vegetable intake intentions was partly mediated by self‐identification, attitude, and self‐efficacy. Conclusions: These studies shed first light on processes underlying the effect of descriptive social norms on health behavior. A norm describing the behavior of a salient social group leads people to identify more with, have more positive attitudes toward, and feel more self‐efficacious regarding that behavior.