This study tested the effect of a message describing a social norm of egalitarian attitudes and behaviors in an engineering college on male students' attitudes and behavioral intentions surrounding diversity in engineering. Participants were first-semester university students enrolled in four sections of an introductory engineering course in two academic terms (Fall 2009 and Fall 2011). At the beginning of the semester, students in two of the four sections received the egalitarian social norms message in the form of an oral presentation given by a senior White male faculty member (social norms message condition). Students in the other two sections did not receive this presentation (control condition). At the end of the semester, all students were invited to complete a survey. Results from a sample of 129 students showed that compared to the control condition, male students in the social norms message condition had stronger intentions to speak out against racist behaviors in their engineering courses and teams, and (among White compared to racial minority men) more positive attitudes toward diversity in engineering. These results suggest that setting a tone of egalitarianism and intolerance of bias for incoming students could help create a more inclusive environment in a White male-dominated educational setting such as a college of engineering.