Over the past two decades, South Africa has sought to perform several roles on the world stage, such as the economic dynamo of Southern Africa, a diplomatic heavyweight representing the African continent, and a norm leader on the world stage as a so-called ‘middle-power’. Although South Africa's evolution and rise as an important player in global affairs has generated a welcome body of critical scholarly literature, comparatively little analysis has been allocated to understanding how norm dynamics and the country's ever-evolving international identities have enabled it to construct and reconstruct its ‘interests’. Social constructivism is best suited for such an analysis because it can operationalise norms, commitments, identities, and interests, and it provides the epistemological tools to map the increasingly multilateral connections between global, regional, and domestic forums. By employing a rationalist approach to constructivism, this paper remedies the aforementioned gap in the literature by illustrating how South Africa constructs and reconstructs its identities and interests in relation to membership in international organisations (IOs). To that end, the paper examines the evolution of South Africa's participation in the African Union (especially ‘peacekeeping’ contributions) and the International Criminal Court. The paper concludes by assessing the theoretical implications and practical ramifications of the norm dynamics involved in South Africa's commitment to these two IOs.