The effects of undergraduate research participation are well documented, but less is known about students' pathways into undergraduate research participation. This mixed-methods study explored the role of an International Baccalaureate research project in students' development of research self-efficacy in high school, and how this development influenced students' participation in undergraduate research. Social Cognitive Career Theory (Lent, Brown, & Hackett, 1994) was used to understand students' learning experiences and educational decision-making processes related to conducting research. Findings were based on analyses of data gathered through a survey, student records analysis, interviews, and focus groups. Findings of this study suggest that students' precollege research experiences enhance research self-efficacy, which leads to interest in and confidence with conducting research during college.