<p>A lack of a sense of belonging within male-dominated fields has been found to explain the underrepresentation and high attrition of women in engineering. Extending social identity theory, this study aimed to explore whether traditional gender role attitudes (GRAs) in engineering classrooms serve as cues to gender identity threat. Whether gender role mindsets (GRMs) in classrooms act as gender identity safety cues that buffer the threat’s effect on female undergraduates’ sense of belonging was also investigated. Study 1 examined whether perceived GRMs in classrooms moderated the mediating effect of perceived traditional GRAs in classrooms on the sense of belonging to engineering majors through gender identity threat perceptions in a sample of 607 engineering undergraduates. The results revealed that the negative indirect relationship between traditional GRAs in classrooms and sense of belonging, mediated by gender identity threat, was significant for women who perceived moderate or higher levels (more fixed) of GRMs in classrooms. This conditional indirect effect was observed only in women (not in men) engineering undergraduates. Study 2 aimed to provide causal validation of the buffering effects found in Study 1 by manipulating classroom GRM beliefs. The results supported the proposed moderating effects of GRMs. Multilevel analysis revealed that the relationship between gender identity threat perception and sense of belonging was not significant among women engineering students only.</p>