Chapter 4 investigates Augmented Human Development across world regions and focuses on the differences between advanced countries (the OECD) and the rest of the world over time. It takes a closer look at world regions, examining the contribution of each dimension to AHD gains and how they affect world distribution. Finally, it investigates catching up to the OECD in the regions of the Rest and what drives it. Augmented human development achieved substantial but unevenly distributed gains across world regions. Life expectancy and schooling drove AHD in both the OECD and the Rest. Although the absolute gap between the OECD and the Rest deepened over time, the gap shrank in relative terms since the late 1920s, at odds with the increasing relative gap in terms of GDP per head. The gap between the OECD and the Rest dominated AHD international distribution until the mid-twentieth century. Life expectancy and civil and political rights were its main drivers of the Rest’s catching up to the OECD. Up to 1970, stronger catching up took place up to 1970, as the epidemiological transition spread and, again, in the 1990s, when liberties expanded in the Rest.