Project Abstract The purpose of this K99/R00 Pathway to Independence award is to enable Dr. Sartin to gain the experience and skills necessary to become an independent investigator focused on identifying, understanding, and eliminating disparities in transportation and pediatric unintentional injuries. Dr. Sartin’s primary objective is to utilize a breadth-to-depth approach that integrates knowledge obtained from population- (breadth) and individual-level (depth) analyses to understand where and why racial and ethnic disparities in child occupant safety arise across the crash injury continuum. In the K99 phase of this project, Dr. Sartin will complete multiple research and training activities to develop knowledge and skills in: (1) advanced epidemiologic/statistical and injury methodologies; (2) management, analysis, and visualization of large databases; (3) advanced R programming; and (4) effective and ethical approaches to researching health disparities. Specifically, Dr. Sartin will complete structured coursework and guided independent study, as well as mentored research with her experienced, interdisciplinary team of mentors and advisors to successfully achieve three aims. In the K99 phase, Dr. Sartin will utilize innovative methods to: analyze a large, unique source of state-level data to determine population-level frequency of child restraint system use across racial/ethnic populations (Aim 1a); identify factors that contribute to lower rates of child restraint system use in minority groups (Aim 1b); and assess how child, driver, and vehicle characteristics impact racial and ethnic disparities observed in child occupants’ crash injury severity (Aim 2). In the R00 phase, Dr. Sartin will recruit recently crash-injured children and a caregiver to participate in a mixed-methods, pilot cohort study—involving surveys, clinical assessments, and semi-structured interviews—to assess short- and long-term mental and physical health outcomes (Aim 3). Findings of the R00 study will serve as preliminary data to support Dr. Sartin’s first R01 proposal. In addition to preparing Dr. Sartin for an independent research career, this work is significant in that it will directly address several critical gaps in child occupant safety. While overall child occupant fatality rates have decreased since 1975, ~3 children die in crashes each day and ~100k more are treated each year in emergency departments for injuries. Further, while overall fatalities have declined, racial and ethnic disparities have widened such that Black children are twice as likely as White children to die in a crash. The high burden and costs of crashes on children ($530M annually) coupled with clear disparities underscore the critical need to enhance child occupant safety, in particular among racial and ethnic minorities. The knowledge gained by this project will ultimately reduce overall rates of pediatric crash injury and death by bolstering protective efforts for the most vulnerable children...