Extant scholarship has until now relied on informal-theoretic, case study, and interpretative methods to assess patterns of norm development in cyberspace. Ideally, these accounts would be complemented with more systematic cross-national and longitudinal empirical evidence. To address this gap, this article introduces the International Cyber Expression Dataset. The dataset includes a corpus of more than 34,000 official expressions of view by states and their authorized representatives regarding the international politics of cyberspace. The article describes the sources of these data and demonstrates the dataset’s usefulness, with an Online appendix containing an exploratory analysis of norm convergence. Future research can leverage the dataset to empirically test questions of theory and policy. For example, the dataset can be used to study how foundational theories of norm diffusion apply to cyberspace. It can also be paired with existing cyber conflict datasets to study the conditions under which state practice influences cyber discourse, and vice versa.