OBJECTIVES/GOALS: Underrepresented (UR) biomedical researchers leave research positions at a disproportionate rate. We aim to identify factors associated with confidence in career progression and intent to continue clinical research training in UR post-doctoral fellows and early-career faculty. METHODS/STUDY POPULATION: Building Up is a cluster-randomized trial at 25 academic institutions. In September-October 2020, 224 participants from the Building Up study completed the pre-intervention assessment, which included questions on demographics, science identity, mentoring competency, confidence in career progression, and intent to continue clinical research training. Using multinomial logistic regression controlling for gender and race/ethnicity, we identified factors associated with confidence in career progression, and intent to continue clinical research training. Statistically significant findings are reported. RESULTS/ANTICIPATED RESULTS: The cohort (N=219) is 80% female, 33% non-Hispanic Black, and 34% Hispanic. Having mentors that address diversity was associated with belief that career advancement is as open to them as anyone else (OR=1.7) and confidence in ability to overcome professional barriers (OR=1.4). Higher science identity (OR=4.0) and having mentors who foster independence (OR=1.7) were associated with confidence in ability to progress in career. Higher science identity was also associated with confidence in ability to overcome professional barriers (OR=2.2) and intent to continue studying biomedical sciences (OR=3.4). Being faculty (OR=3.8), higher science identity (OR=3.8), and having mentors that align expectations (OR=2.3) were associated with intent to continue clinical research training. DISCUSSION/SIGNIFICANCE: These findings suggest that science identity and mentoring play key roles in confidence in career progression and intent to continue clinical research training. These factors are important to consider in retaining UR early-career biomedical researchers.