Brownell has investigated the origins of the gender gaps in science, with a specific focus on achievement and participation in biology. Her research has shown that male students are more self-confident than their female counterparts in their science classes. These differences in self-perception can impact motivation and participation. She identified that undergraduates who experience a positive lab environment are considerably more likely to complete a degree in STEM. She has investigated how students from marginalized groups experience active learning, and why educators from underrepresented groups may disclose their identities to students. In particular, Brownell showed that active learning forces students to interact with one another, which can make LGBTQ+ students feel like they have to "come out".
