This chapter explores two competing Catholic conceptions of social justice. The first strand of Catholic social justice, rooted in Pope Leo XIII’s 1891 encyclical Rerum Novarum and subsequent papal interventions, promoted a social order based upon traditional familial structures. This ‘organicist’ ideal of social justice originally aimed at combatting Marxism, the ills of industrialization, and the erosion of the Church’s influence in European public life. Although the Vatican-endorsed model of social justice predominated within the Church, not all Catholics embraced the anti-Communism and emphasis on the patriarchal family that ‘organicist’ social justice ideas promoted. The second, more decentralised strand of Catholic social justice – the ‘radical’ model – sprang from disagreements within the Church on how to respond to socialism, workers’ rights, dechristianisation, and decolonisation. ‘Radical’ social justice enjoyed support from grassroots activists, theologians, reformers, and other Church leaders who endeavoured to empower the powerless in their societies and, from the 1950s and 1960s, around the world. Both strands of social justice upend conventional distinctions between the political left and right, while also bridging the national and the transnational. By problematizing the political and spatial categories commonly used to discuss social justice, this chapter offers a useful corrective to existing social-justice narratives.