1 Nigerians make up a significant proportion of individuals in Africa dying from human papillomavirus-(HPV) 2 associated cancers. However, they do not access essential cancer prevention services such as evidence- 3 based HPV vaccination to prevent cancer. This is partly explained by barriers that are individual (low 4 awareness), social (insufficient social support), and structural (poor access to vaccines). Implementation of 5 HPV vaccine programs can mitigate some of these barriers by decentralizing vaccine access to reduce the 6 incidence and death rate of HPV-associated cancers. We propose to expand youth-friendly HPV vaccines, 7 informed by a youth participatory action research framework (YPAR), the PEN-3 cultural model, and the 8 Consolidated Framework for Implementation Science (CFIR). Unlike projects targeting youth as passive 9 recipients, the YPAR considers youth to be partners in creating and leading solutions to problems that affect 10 them. PEN-3 cultural model leverages local resources and partnerships from an equity mindset to improve 11 health, while CFIR enables an evaluation of the barriers and facilitators of implementation effectiveness. The 12 proposed Innovative Tools to Expand youth-friendly Services and Translation of HPV services (I-TEST HPV) 13 will draw on two participatory methods, crowdsourcing (i.e., open calls and designathons) and apprenticeships, 14 to increase HPV vaccine uptake among girls aged 9-15 years old per national guidelines. We hypothesize that 15 these two approaches (open challenges and apprenticeships) will increase the uptake of HPV vaccine 16 campaigns in Nigeria. Using a hybrid type II effectiveness implementation design to simultaneously assess 17 both clinical and implementation outcomes, our aims are: 1) To use participatory approaches (crowdsourcing 18 and apprenticeships) to develop new HPV vaccine campaigns; 2) To determine whether the final 19 crowdsourced campaign increases HPV vaccination uptake among girls aged 9-15 years, and evaluate 20 intervention sustainment, one-year post implementation. We will recruit 1,120 girls from 32 communities to a 21 stepped-wedge randomized control trial of the finalist campaign versus usual care. A total of sixty-four trained 22 youth research facilitators from each setting (2 per setting) will implement the final HPV vaccination campaign. 23 The primary outcome is the initial HPV dose vaccine uptake among girls ascertained by vaccination records at 24 community clinics. The secondary outcomes include the second vaccine dose, percent sustainment of core 25 program elements with sustained benefits (uptake of HPV vaccines), and sustained capacity at participating 26 communities at one year after the trial; and 3) To use mixed-methods to explore multilevel factors that 27 influence the uptake of the HPV campaigns. This research aligns with the RFA-CA-11-019 request for research 28 and the US Cancer Moonshot Initiative. The project builds on a strong...