Project Summary Sudden and Unexpected Infant Deaths (SUID), which include Sudden Infant Death Syndrome and unintentional injury-related infant deaths, remains a leading cause of US postneonatal mortality, with ~3400 deaths/year. Many SUIDs are preventable with greater adherence to safe infant sleep guidelines. There are racial and socioeconomic disparities in adherence to these guidelines and in SUID rates. We conducted the successful Social Media and Risk-Reduction Training for Infant Care Practices (SMART; 1R01HD072815) study in which 1600 mothers at 16 US birth hospitals were randomized to receive short educational videos, delivered by email or text message, focused on safe sleep (TodaysBabyTM) vs. control, in the first 2 months after birth. Compared to mothers receiving attention-matched control messages, those receiving this intervention had ~10 percentage point higher rates of following safe sleep practices. Importantly, racial and socioeconomic disparities in safe sleep practices were eliminated among the study population. Given that we have demonstrated effectiveness in the SMART intervention, we now propose GET SMART (Get Social Media and Risk-Reduction Training), a type 3 hybrid implementation-effectiveness cluster randomized trial of 20 hospitals to determine optimal strategies to implement this intervention in real-world conditions. We will compare the “high touch” (HT) implementation strategy used in SMART (hospital staff introduced the program, obtained informed consent, watched 2 videos with them) with a “low touch” (LT, i.e., less resource-intensive) strategy, which will leverage social marketing techniques in a direct-to-consumer approach to reach mothers during the postpartum hospitalization through QR codes easily visible in the hospital environment that mothers will use to sign up for the TodaysBabyTM program. Given the disparities in SUID and safe sleep practices, GET SMART will occur in hospitals serving predominantly low-income populations in counties with >1.5 times the national SUID rate. We will use the Proctor Conceptual Model of Implementation Research to inform our implementation strategies and outcomes. We will compare the impact of the hospital-based HT and LT strategies with regards to differences in penetration (proportion of eligible mothers who sign up for TodaysBabyTM), equity of penetration according to income and race/ethnicity, and the program cost per mother sign up. Secondary implementation outcomes will be feasibility, acceptability, sustainability; and fidelity to the intervention (number of videos watched). Effectiveness outcomes will be adherence to 4 safe sleep practices (sleep position, sleep location, nonuse of soft bedding, pacifier use) after the 2-month intervention. After completion of this implementation-effectiveness study, we will be able to generate valuable policy-relevant data for an easily replicated mobile-delivered video safe sleep intervention needed for decision-making by public healt...