BRAINS: Broadening the Representation of Academic Investigators in NeuroScience is a National Institutes of Health-funded, national program that addresses challenges to the persistence of diverse early-career neuroscientists. In doing so, BRAINS aims to advance diversity in neuroscience by increasing career advancement and retention of post-PhD, early-career neuroscientists from underrepresented groups (URGs). The comprehensive professional development program is structured to catalyze conversations specific to URGs in neuroscience and explicitly addresses factors known to impact persistence such as a weak sense of belonging to the scientific community, isolation and solo status, inequitable access to resources that impact career success, and marginalization from informal networks and mentoring relationships. While we do not yet have data on the long-term impact of the BRAINS program on participants' career trajectory and persistence, we introduce the BRAINS program theory and report early quantitative and qualitative data on shorter-term individual impacts within the realms of career-advancing behaviors and career experiences. These early results suggest promising, positive career productivity, increased self-efficacy, stronger sense of belonging, and new perspectives on navigating careers for BRAINS participants. We finish by discussing recommendations for future professional development programs and research designed to broaden participation in the biomedical and life sciences.