Social Risk Screening and Referral Implementation for All Pediatric Hospitals – The SOCIAL-H Study - Social determinants of health are widely recognized to impact child health across the life course. Evidence demonstrates that social risk screening and referral in ambulatory settings benefits child health and increases family connections to community resources. Professional guidelines from the American Academy of Pediatrics therefore recommend integration of social risk screening into routine pediatric care, and multiple regulatory bodies, including the Centers for Medicare and Medicaid Services, recently launched standard-setting initiatives requiring social risk screening and referral for hospitalized patients. However, we understand very little about screening and referral in pediatric inpatient settings, leaving critical knowledge gaps regarding how to best implement social risk screening and referral in pediatric hospital environments. As patients facing social stressors are known to have less access to primary care and increased hospital use, pediatric hospitalization represents a uniquely opportunistic time to screen for social risks and intervene prior to consequent health outcomes. My long term goal is to utilize implementation science methods to promote integration of social risk screening and referral interventions into pediatric inpatient care to improve health outcomes and hospital utilization for medically and socially vulnerable children. Leveraging a natural experiment, our objective in this proposal is to gain understanding on how to best implement social risk screening and referral across all types of hospitals caring for children in the US. We plan to accomplish this goal through three specific aims: (1) survey and interview clinical leaders from a national network of hospitals, including freestanding children’s hospitals, nested pediatric hospitals, and community hospitals, assessing facilitators and barriers experienced during implementation of social risk screening and referral across hospital types; (2) create an implementation toolkit for pediatric inpatient social risk screening and referral programs, by identifying and prioritizing implementation strategies to address barriers utilizing a modified-Delphi approach with a national panel of multidisciplinary hospital stakeholders; and (3) pilot the toolkit, assessing implementation and preliminary effectiveness at one tertiary and one community hospital. Completion of this research may promote and hasten successful integration of social risk screening and referral into routine pediatric inpatient care, aligning with professional guidelines and national standard-setting initiatives, and has potential to improve child health and hospital utilization. My complimentary training in implementation science frameworks, advanced mixed methods, multistakeholder-engaged research methods, and pragmatic intervention trials will propel these aims, facilitate my leading future hybrid effectiveness-implementation trials, and will bring me closer to my career goal of becoming an independent implementation scientist, focused on developing, implementing, and evaluating interventions to improve child health and hospital utilization for vulnerable pediatric populations.