Curricular content in undergraduate biology courses has been historically hetero and cisnormative due to various cultural stigmas, biases, and discrimination. Such curricula may be partially responsible for why LGBTQ+ students in STEM are less likely to complete their degrees than their non-LGBTQ+ counterparts. We developed Broadening Perspective Activities (BPAs) to expand the representation of marginalized perspectives in the curriculum of an online, upper-division, undergraduate animal behavior course, focusing on topics relating to sex, gender, and sexuality. We used a quasiexperimental design to assess the impact of the BPAs on student perceptions of course concepts and on their sense of belonging in biology. We found that LGBTQ+ students entered the course with a better understanding of many animal behavior concepts that are influenced by cultural biases associated with sex, gender, and sexuality. However, LGBTQ+ students who took the course with the BPAs demonstrated a greater sense of belonging in biology at the end of the term compared with LGBTQ+ students in the course without BPAs. We also show that religious students demonstrated improved comprehension of many concepts related to sex, gender, and sexuality after taking the course with BPAs, with no negative impacts on their sense of belonging.