Every hour, over 150 people die of hepatitis-related liver diseases in African countries like Nigeria, including hepatocellular carcinoma (HCC) and other liver cancers. Much of this death is attributable to the hepatitis B virus (HBV). A hepatitis B birth dose (HepB-BD) vaccine initiated within 24 hours of birth, followed by three additional pentavalent HBV vaccines (at six, 10, and 14 weeks after birth), provide durable immunity, substantially decreasing the risk of HBV and liver cancer. Nigerian national guidelines recommend HepB-BD vaccination for all newborns and provides them for free as part of the national immunization protocol, yet uptake is suboptimal, highlighting the need for implementation science research to develop locally relevant strategies to increase HepB-BD vaccine uptake. We propose a crowdsourcing approach to enhance timely coverage of HepB-BD vaccination in Nigeria. Crowdsourcing has a group of people solve all or part of a problem, then implement selected solutions. Our team used crowdsourcing to develop messages promoting HBV testing uptake, inform global hepatitis guidelines, and enhance hepatitis community engagement in low and middle-income countries (LMICs). Our study will focus on developing and implementing strategies to increase HepB-BD vaccination at community clinics, home births, and other sites outside of hospitals where most pregnant women receive care. The Consolidated Framework for Implementation Science Research (CFIR) and concept mapping will guide our evaluation of factors influencing uptake and sustainment. Our specific aims are: 1) To determine pregnant women's preferences on HepB-BD vaccination using community-engaged crowdsourcing research and finalize an implementation strategy to increase HepB-BD vaccination; 2) To determine the effectiveness of a finalized crowdsourced HepB-BD vaccination intervention among a cohort of pregnant women using a community-based clinic-level cluster RCT. Trained community health workers will implement the final intervention in a cluster randomized control trial of the crowdsourced intervention versus standard care (i.e. printed guidelines) among a cohort of 720 dyads (pregnant women and newborns) at 36 community-based clinics (n=1440); and 3) To use mixed methods research to determine multi-level factors that influence uptake and sustainment of crowdsourced HepB-BD vaccination over time. Primary outcome is HepB-BD vaccination ascertained by clinic records. Secondary outcome is service sustainment at the community-based clinic level, defined here as the percent sustainment of core elements of the final campaign measured 12 months after the trial, with sustained benefits and capacity for implementation at each community-based clinic. Our study is responsive to the U54 request for applications for global implementation science for equitable cancer control and and the strategic priorities of the National Cancer Institute. This study will provide a unique opportunity to expan...