The global health agenda—a high stakes process in which problems are defined and compete for the kind of serious attention that promises to help alleviate inequities in the burden of disease—is comprised of priorities set within and among a host of interacting stakeholder arenas. This study informs crucial and unanswered conceptual and measurement questions with respect to civil society priorities in global health. The exploratory two-stage inquiry probes insights from experts based in four world regions and pilots a new measurement approach, analysing nearly 20 000 Tweets straddling the COVID-19 pandemic onset from a set of civil society organizations (CSOs) engaged in global health. Expert informants discerned civil society priorities principally on the basis of observed trends in CSO and social movement action, including advocacy, program, and monitoring and accountability activities—all of which are widely documented by CSOs active on Twitter. Systematic analysis of a subset of CSO Tweets shows how their attention to COVID-19 soared amidst mostly small shifts in attention to a wide range of other issues between 2019 and 2020, reflecting impacts of a focusing event and other dynamics. The approach holds promise for advancing measurement of emergent, sustained and evolving civil society priorities in global health.