Field courses have been identified as powerful tools for inclusion and student success in science. However, not all students are equally likely to take field courses. How do we remove barriers to equity in field courses, to make them engines for inclusion, diversity, and collective excellence in ecology and evolution? How Can Field Courses Be Catalysts, not Barriers? Ecology and evolutionary biology (EEB) lags other subfields of biology such as the biomedical sciences, in diversity and inclusion [e.g., in the USA, 5.8% of EEB graduate students are from under-represented minority (URM) backgrounds, compared with 10.1% in biomedical sciences] [1]. Students from under-represented racial, cultural, economic, and other backgrounds drop EEB majors at higher rates than their peers, in part because of hurdles like institutional barriers and a limited sense of belonging [2,3]. We highlight how field-based courses can be a powerful vehicle for addressing demographic gaps in EEB, and we provide guidance for inclusive field course design. A well-structured field research course can inspire and prepare students for scientific careers (self-efficacy, science identity, and competence), and create shared experiences and relationships that retain students who might otherwise feel disconnected from their backgrounds and previous experiences (identity, belonging, and community) [4,5]. Participation by URM students in fieldbased science courses has often been low [4], creating the impression that field courses are not a path to increased STEM (science, technology, engineering, and mathematics) inclusion. We contend that barriers, like cost, schedules, information, specialized equipment, and a lack of staff role models, reduce access and participation (Figure 1). Removing these barriers enables diverse students to pursue field experiences, propelling more diverse leadership, cultural change, and collective excellence in ecology and evolution.