This is the first in-depth, English-language study of Romania's role in the Little Entente-an alliance formed with Czechoslovakia and Yugoslavia to defend the territorial status quo in Central and Eastern Europe after the First World War . While this alliance has often been dismissed in international historiography as peripheral, this book argues that the Little Entente was a critical, albeit fragile, experiment in regional security and interwar diplomacy. Anchored in Romania's foreign policy, it reinterprets the alliance as a revealing case study in small-state agency, collective security, and the entropic pressures of the post-war order. Whilst drawing on a wide range of Romanian diplomatic archives, press materials, and memoirs, many of which remain underutilized in anglophone scholarship, Grey also situates Romania's actions within the larger European context, assessing how regional alliances engaged with the League of Nations and evolving relationships with France, Germany, Italy, and Soviet Russia. Romania, the Little Entente and the Struggle for Europe moves beyond simplistic narratives of failure and instead presents a nuanced portrait of the Little Entente as a fragile, flawed, but earnest effort to secure peace in a precarious international order-one whose lessons resonate powerfully today.