Progress towards UHC is a continuous process that changes in response to shifting demographic, epidemiological and technological trends, as well as people’s expectations. The goal of the service coverage dimension of UHC is that people in need of promotive, preventive, curative, rehabilitative or palliative health services receive them, and that the services received are of sufficient quality to achieve potential health gains. A UHC service coverage index – a single indicator computed from tracer indicators of coverage of essential services – was developed to monitor SDG indicator 3.8.1. For the first time, this report presents methods and baseline results for 183 countries for the index. The UHC service coverage index is straightforward to calculate, and can be computed with available country data, which allows for country-led monitoring of UHC progress.