This report summarizes progress made during STOP Spillover's first year of project implementation from October 2020 through September 2021. Year 1 focused on initiation of STOP Spillover in four countries, Uganda, Liberia, Bangladesh, and Viet Nam. The first year was defined by deep engagement with countries, key stakeholders, and communities. Their contributions and guidance have helped to ensure that STOP Spillover's approach is inclusive and will have a sustainable impact on decreasing risk of zoonotic viral spillover.