Our multidimensional assessment of social sustainability in Peru and South Africa shows that on average 67 percent and 65 percent of the Peruvian and South African population, respectively, experience overlapping social gaps—defined as experiencing gaps in least a third of the social dimensions considered. These rates are much higher than their official income poverty rates of 30 and 57 percent, respectively.<sup>15</sup> These people experience an intensity rate of 47 percent in Peru and 53 percent in South Africa, equivalent to 7 and 8 indicators, respectively. Women are especially affected in South Africa, but much less so in Peru. Ethnic populations experience greater levels of social gaps in both countries. Geographically, we find that South African provinces show greater disparities compared to departments in Peru. Our analysis also shows that these findings are robust to changes in the cross-dimensional threshold, confirming patterns of multiple social gaps by gender and ethnicity as well as the drivers found with the 33 percent threshold.

Our measurement approach has several limitations. First, current microdata sources at the individual and household levels fail to provide rich evidence for all of the dimensions of social sustainability. While most household surveys provide a comprehensive diagnostic of access to markets and services, they fail to simultaneously capture issues of trust, satisfaction, participation, and accountability; South Africa and Peru are rare exceptions where comprehensive datasets are collected. Hence, even though the mechanics of constructing the index are replicable across countries, the choice of indicators and the composition of the Social Sustainability Index will inevitably vary based on data availability. Second, some of the most vulnerable population groups remain virtually invisible to household surveys. This is notoriously the case of LGBTI people and irregular migrants. Other disadvantaged population groups in terms of race, ethnicity or disability are more frequently identified in standard household surveys, but their sampling is typically not designed to be statistically representative. Addressing such challenges requires huge efforts in harmonizing national household surveys worldwide; expanding the number and scope of questions typically collected by censuses; and improving sampling methods for household surveys.

Yet challenges in defining social sustainability do not automatically mean that measuring multiple social gaps is impossible. Moves towards more inclusive and harmonized data are already underway. Some examples include the <mark>Integrated Public Use Microdata Series managed by the Minnesota Population Center; the development of disability statistics suitable for census and national surveys by the Washington Group; efforts by the World Bank’s Global Monitoring Database to produce comparable poverty statistics worldwide; or the Inclusive Data Charter sponsored by the UN. S</mark> imilar methodological challenges have been overcome in the past: witness systems that monitor global food prices and warn of acute food insecurity; the internationally agreed system of national accounts; definitions and measurement of decent work; or international statistics on crime and justice. <mark>Clearly, greater a</mark> nd better-coordinated efforts are still needed before we can measure social sustainability at a granular level and on a global scale. But both previous and current experiences offer lessons about the value of concerted action, arriving at technical agreements, operationalizing monitoring, and using data for effective policy making.

In the meantime, national estimates of multidimensional social sustainability and its fragilities in the form of social gaps, as produced here for South Africa and Peru, still provide impactful findings for policy makers. Threats to social sustainability are driven primarily by process legitimacy in both countries. These results not only confirm the multidimensional nature of social sustainability, but also the need for intervention packages separate from other policies related to poverty reduction,

> 15 Official reports in Peru come from INEI (2022) and in South Africa from STATSSA (2022).

27