The recent proliferation of referendums on sovereignty matters has fuelled growing scholarly interest. However, comparative research is hindered by the weaknesses of current compilations, which tend to suffer from conceptual vagueness, varied coding decisions, incomplete coverage and ad hoc categorizations. Based on an improved conceptualization and theory-driven typology, this article presents a new dataset of 602 sovereignty referendums from 1776–2012, more than double the number in existing lists. In an exploratory analysis, it uncovers eight distinctive clusters of sovereignty referendums and identifies patterns of activity over time and space as well as outcomes produced.