Scholars of the history of international law have recently begun to wonder whether their work is predominantly about law or history. The questions we ask – about materials, contexts and movements – all raise intractable problems of historiography. Yet, few scholars have turned to historical theory to think through how we might go about addressing them.This article works towards remedying that gap by exploring why and how we might engage with historiography more deeply.Section 2 shows how the last three decades of the ‘turn to history’ can be usefully read as a move from ambivalence to anxiety. The major works of the 2000s thoroughly removed the pre-1990s ambivalence to history, offering brief considerations about method. Recent efforts building on those works have led to the present era of anxiety about both history and method, raising questions around materials, contexts and movements. But far from a negative state, this moment of anxiety is both appropriate and potentially creative: it prompts us to rethink our mode of engaging with historiography.Section 3 explores how this engagement might proceed. It reconstructs the principles and debates within conceptual history around the anxieties of materials, contexts and movements. It then explores how these might be adapted to histories of international law, both generally and within one concrete project: a conceptual history of recognition in the writings of British jurists.Section 4 concludes by considering the advances achieved by this kind of engagement, and reflects on new directions for international law and its histories.