Studies indicate that racial disparities in STEM achievement or equity grade gaps are associated with faculty fixed mindset beliefs; however, whether specific instructional beliefs are linked to student academic achievement remains unclear. We surveyed 216 STEM faculty to assess their mindset and instructional beliefs and linked these to detailed student transcript data (n = 31,361). Results reveal that faculty with fixed mindset beliefs also endorsed more traditional instructional beliefs regarding assessment, grading, and diversity. Further, the endorsement of these beliefs was associated with larger equity grade gaps. Analysis of faculty characteristics indicate that male faculty, full professors, and instructors in Physical Sciences tended to hold instructional beliefs that are linked to larger equity grade gaps.