PROJECT SUMMARY/ABSTRACT Pre-Exposure Prophylaxis (PrEP) is becoming increasingly available in sub-Saharan Africa (SSA) and as a highly effective and user-controlled intervention for HIV prevention holds promise for those most at risk of infection including adolescent girls and young women (AGYW). However, most of the increased uptake of PrEP in SSA has been in a handful of countries with the world’s highest HIV rates, and where the HIV prevalence can influence risk perception and willingness to use PrEP. Despite the rise PrEP in these and other regions where it is available, most of those eligible for PrEP are not using it, and among those that do begin PrEP, discontinuation rates in the months after initiation is common, especially for AGYW, In West Africa, where HIV rates are lower but unacceptably high, PrEP is beginning to be rolled out. Public health authorities in Liberia have taken steps to integrate PrEP into the country’s HIV prevention programming and have recently started pilot clinics to administer PrEP to men who have sex with men, transgender women, and people who inject drugs. In 2023-24, PrEP will be expanded nationwide to include the largest key population AGYW. These policymakers are deeply interested in developing PrEP programming that is preference-sensitive and reflects determinants of PrEP engagement for AGYW in the West African context, which is distinct from those of other regions of Africa. Therefore, we propose to obtain an in-depth understanding of the PrEP perceptions and preferences among urban and rural AGYW in Liberia, their male partners, and healthcare providers – applying the situated Information, Motivation, and Behavioral Skills (sIMB) model to guide our investigations. In close collaboration with PrEP planners, we will then use Intervention Mapping framework processes to directly apply the formative data to the development of implementation planning for PrEP for AGYW. The resulting implementation options will serve as a roadmap for the critical next stage of PrEP roll-out in Liberia and serve as a model for similar settings.