Scholarship of unrecognised states tends to emphasise differences between de jure and de facto sovereignty. However, such research generally lacks a clear theoretical grounding for what defines de facto sovereignty, and paradoxically appears reluctant to abandon non-material notions of this concept. Therefore, this article proposes a classical realist conception of de facto sovereignty as a helpful contribution to studies of unrecognised states, regarding it as the ‘real’ act of supreme and absolute power that fully politically separates one political entity from another. To illustrate this claim, this article focuses on the emergence and demise of the early-1990s Kosovar ‘parallel state’.