Background: Despite long-standing initiatives to improve gender equity across STEM fields, women's representation in undergraduate engineering programs remains low. STEM faculty, as influential gatekeepers, can promote gender inclusivity in these fields. Yet, little is known about how faculty construct their responsibilities to advance gender equity. Purpose/Hypothesis: We investigated how STEM faculty teaching first-year engineering courses constructed teacher identities and responsibilities. Our research questions included: What discourses do faculty use to construct the meaning of student gender expression in their classroom? How do faculty discursively position themselves in relation to gender equity? What teacher identities and responsibilities do they construct through these discourses? Design/Method: Utilizing a feminist, poststructural epistemology and discursive methodology, we analyzed 18 interviews with instructors in three undergraduate engineering programs. After coding data for ways instructors talked about gender in their work with students, we analyzed how faculty constructed their teacher identities in relation to each discourse and how these positions affected their promotion of gender equity. Results: Faculty used three dominant discourses to construct student gender expression and teacher identities: gender blindness, gender acknowledgment, and gender intervention. Faculty most frequently utilized discourses acknowledging gender inequity, which often limited their responsibilities to promote equity and highlights the pernicious nature of systemic gender bias. Conclusions: Findings suggest that institutions could expand discourse and better align faculty awareness of gender inequity with meaningful, pedagogical change strategies.