Focusing on the internet as a foundational technology, this paper begins by summarising recent developments in digital inclusion theory, particularly as this relates to developing countries. It sets out a framework of core components of digital inclusion - including access/use, quality of access/use, affordability, and digital skills - and briefly considers policy implications. The paper then surveys the ways these components are currently measured in household and firm surveys and by international organisations, highlighting some of the often-overlooked weaknesses of current measures, and suggesting possible improvements. The paper also reflects on potential applications of (and risks associated with) new ways of measuring digital inclusion using big data. Lastly, building on the framework developed, the paper reviews the empirical literature on ‘digital divides’ in developing countries, and makes suggestions for how future research could become more rigorous and useful.