Objective <p>Innovation in psychiatry relies on laboratory-based neuroscience research using experimental animal models. How to best train and support investigators remains a critical question for the field. We examined how training background, operationalized as MD, PhD, or MD/PhD degree, is associated with National Institutes of Health (NIH) K-to-R01 transition, a key career benchmark. Understanding how clinical and research training impact early research success will inform strategies in medical education and physician-scientist training in psychiatry.</p> Methods <p>This preregistered study used NIH RePORTER to identify recipients of NIH mentored-career-development K01 and K08 awards from neuroscience-focused NIH institutes. Projects using animal models to address a neuroscience question were identified by title-and-abstract review. R01 awards (1997–2024) were identified and linked to prior K awardees (1997–2016) to determine conversion rates.</p> Results <p>Among 758 awards (243 K01, 515 K08), 51% (388/758) converted to at least one R01. Conversion rates differed significantly by degree (<i>p</i> = 0.035). MD-only investigators were less likely to convert (44%, 86/197) than MD/PhD (55%, 184/333) or PhD (52%, 118/228) investigators. Time to conversion also differed (<i>p</i> = 0.032), with longer duration for MD-only investigators. In exploratory analyses, male PhDs converted more often than females (59% vs. 41%; <i>p</i> = 0.024). No sex difference was found for MD and MD/PhD investigators.</p> Conclusions <p>Lack of PhD-level research training was associated with reduced and delayed K to R01 transition for investigators using experimental animal models in neuroscience. Integrating PhD-style research training elements into psychiatry residency and faculty development programs may help close training-related gaps and address emerging sex disparities in research advancement.</p>