Undergraduate research is becoming the norm for undergraduate STEM majors, with summer undergraduate research programs being one such way students receive this experience. These summer programs are known to have many positive outcomes for students, such as bolstered confidence, retention in STEM majors with continuation into science graduate programs and careers, and socialization into the science research culture. The majority of research on this subject, however, is drawn from programs that are small/one-site, large/multi-site from the same national funding source but with each site running independently, or is survey research drawn from individuals across many different programs. The present research provides a unique contribution to the literature regarding the outcomes of the Amgen Scholars Program multi-site, unified, international undergraduate summer research program. In addition the article also examines and provides recommendations for future research directions for such programs.