This paper analyses levels and trends in within-country income inequality during the second-half of the 20th century. Two broad general trends were visible: beginning in the 1950s and 1960s inequality declined substantially in most countries, and in the 1980s and 1990s it increased more variably and more slightly. However, we focus here on presenting and explaining the distinct ‘macroregional’ regimes of inequality that became evident in this period. We identify six: Anglo, Nordic, Continental West European, Latin American, East Asian and South Asian. We show that intra-regional variations in inequality have been much less than inter-regional variations, and that the six regional regimes did not remain constant but had distinct trajectories through time. The Anglos were at first the most egalitarian, only later developing the greater inequality supposedly characteristic of their ‘liberalism’. The Nordics only became the most egalitarian in the middle of our period. The Euro-Continentals began as the most unequal among the Western countries, but then became almost as equal as the Nordics. Latin America began and remained the most unequal region of all. East Asia was rather egalitarian, while South Asia converged towards a middling inequality. Though pressures towards more inequality strengthened from 1980, regional responses remained varied and path-dependent. Then, in more speculative vein, we seek to explain these regional patterns in macro-sociological terms. Beginning from a model of dynamic interactions between economic, ideological, military and political power relations, we trace the political institutionalization of distinct macro-regional ideologies of ‘best practices’ of socio-economic development.