Each This paper examines the Yalta Conference (4–11 February 1945) as a pivotal episode of post-war order-building and asks what mattered more in shaping its outcomes: material capabilities or institutions. Combining a historical reconstruction of key negotiations—Germany’s occupation and reparations, Poland’s political future, Soviet entry into the war against Japan, and the design of the United Nations—with an explicit International Relations framework, the study evaluates whether Yalta’s model of great-power management stabilized the emerging system or intensified a security dilemma between the Western and Soviet blocs. Methodologically, the paper employs a qualitative case-study design and process tracing, using primary diplomatic records alongside major secondary scholarship to identify bargaining sequences, causal mechanisms, and “close-call” turning points. The analysis argues that power realities set the limits of agreement, particularly where military facts on the ground created asymmetric leverage, while institutional arrangements helped formalize, legitimate, and extend those bargains over time. Yalta therefore reduced the risk of immediate great-power war by coordinating expectations and procedures, yet simultaneously accelerated ideological and strategic competition by embedding contested norms—especially over self-determination—within an unequal settlement. The paper concludes that Yalta’s legacy is best understood as an institutionalized power bargain: stabilizing at the apex, but structurally prone to legitimacy crises at the periphery, shaping both the early Cold War and the architecture of post-1945 global governance.