For 60 years, the National Science Foundation's commitment to undergraduate research experiences has shaped the course of undergraduate research opportunities, from apprenticeship model-based experiences to team-based and classroom-based collaborations for a diverse group of students. Scaling the opportunity so that students may participate in an equitable and inclusive way has been a priority since the inception of the program. Applying the growing research base in undergraduate science, engineering, and mathematics education to development of optimal research experiences for undergraduates is the next frontier.