More diverse representation in undergraduate classrooms may be an important step towards turning science, technology, engineering, and mathematics (STEM) disciplines into more inclusive communities. In the United States of America, the individuals whose work is discussed in typical introductory science courses collectively do not represent the diversity of students’ identities in the classroom and further reinforce existing stereotypes of scientists as male, white, and aged. Here we report on the implementation of a semester-long intervention in an introductory-level geoscience course at the University of South Florida, USA. We introduced students to individuals with marginalized identities who are either scientists or have had a major influence on science and conducted semi-structured interviews with students from the course’s previous semesters. Analyses of these interviews indicate that participants with marginalized and non-marginalized identities broadened their preconceptions of who belongs in science and the range of identities among scientists. We suggest that interventions like these could foster feelings of belonging in the STEM community and, with repeated efforts, reduce harmful stereotyping and microaggressions against underrepresented scientists.