This article explores an attempt by one Polish organisation – known until 1952 by the name of its weekly journal Dziś i Jutro, thereafter as PAX – to assemble a ‘Catholic-socialist’ international in the decade following the Second World War. This transnational project was predicated on co-operation across the Iron Curtain by Catholic thinkers and activists opposed to the rearmament and incorporation of (West) Germany into an integrated European community. The project's author Wojciech Kętrzyński deployed a discourse of protecting the ‘human person’ based on the prioritisation of global peace. Polish encounters with francophone Catholic activists from across Western Europe – especially with the French journal Esprit – bred serious intellectual engagement across the Iron Curtain at the level of Catholic philosophy and theology. Paradoxically, however, these activists accepted that the dignity of the human person would be best served by transnational anti-Germanism, at the price of complicity with – or outright participation in – Stalinism. The self-styled Catholic-socialist project thus failed, yet, surprisingly, it failed neither immediately nor completely. It thus reveals that possibilities existed throughout the cold war – even at the height of Soviet-bloc Stalinism – for intellectual, cultural and political exchanges and partnerships across the Iron Curtain.