Data is a source of power. It can be exploited for private gain, and used to limit freedom, or it can be deployed for the public good: as a resource for tackling social challenges, enabling collaboration, driving innovation and improving accountability. Over the last decade, data has risen to the top of national and global policy agendas: as nations seek to develop their economies, use data to address social challenges, and respond to citizen concerns about the uses and abuses of data. Yet, progress towards effective data governance, and to realising the public value of data, remains highly uneven across countries, regions and sectors. For example, while data protection laws are now widespread across the globe, many lack key redress mechanisms to allow individuals and communities to effectively exercise their data rights, and few comprehensively address emerging issues around location data, or algorithmic decision making. In critical areas like climate action, significant data gaps can frustrate local action to protect ecosystems, and respond to climate vulnerability. And when we look beyond the simple availability of datasets, to examine whether the data provided meets user needs, we find cases of data that's collected and shared, but that lacks key features or quality assurances that would allow it to properly power civic action, improved public services, and economic development. This first edition of the Global Data Barometer provides evidence and insight into the development of national and global data ecosystems: offering critical comparisons, analysis and examples that can help drive top-down and bottom-up action to realize the opportunities of the data revolution, while navigating its risks. In this sense, the Barometer aims not only to produce assessments of countries based on the state of their data, but also to assemble and support collective learning around what works, and about how to effectively intervene with and around data. In this report we summarize a number of key findings, and highlight how the data gathered through the Barometer can be used in further exploratory work.