The representation and retention of learners from marginalized racial and ethnic backgrounds is steadily declining in the sciences. Factors contributing to this disparity include reduced self-efficacy, stereotype threat, limited familial and financial support, insufficient academic preparation, as well as poor teaching techniques. This session proposes instructor misbehavior as an unconventional candidate responsible for modulating the attrition of underrepresented learners in science. Information presented will help attendees (1) identify learner-perceived instructor (mis)behaviors and, by implication, (2) improve the teacher-student/trainer-trainee interaction. Further, session attendees will also contribute to budding discussion to help foster a much-needed typology that describes how racial and ethnic identity influences student perceptions of instructors’ behaviors.