Pathways to biomedical careers are not being pursued with equal vigilance among all students. Emerging research shows that historically underrepresented (HU) students who maintain a strong science identity are more likely to persist. However, the influence of social support on persistence is less studied, especially as it relates to science identity among doctoral students. To fill this gap, a 1-year study to assess similarities and differences among 101 HU and majority biomedical doctoral students was conducted to measure the extent to which 1) they report equivalent experiences of social support, science identity, and intentions to persist; 2) their experiences of social support predict intentions to persist 1 year later; and 3) science identity mediates the relationship between social support and intentions to persist in biomedical career pathways. Data were collected using online surveys. Results indicated that science identity significantly mediated the relationship between professional network support and persistence a year later for majority students. In contrast, for HU students, science identity mediated the relationship between instrumental, psychosocial, friend and family support, and persistence a year later. These study results provide evidence that reinforcing mentoring programs and support systems will be beneficial, especially for HU students.