The present article has examined the effect of the duration of the membership in the General Agreement on Tariffs and Trade (GATT) and/or the World Trade Organization (WTO) (and not the mere membership in the GATT/WTO) on the growth of human development, considered as a measure of citizens' welfare. We hypothesize that by reducing economic growth volatility, the membership duration would promote human development. The analysis has relied on a panel dataset of 148 developed and developing countries, over the period from 1990 to 2019, and provided support for the theoretical hypothesis. Interestingly, the membership duration is always associated with a higher growth of human development, regardless of countries' degree of economic growth volatility. However, the lower the level of economic growth volatility, the larger is the positive effect of the membership duration on the growth of human development. Finally, the effect of the membership duration on the human development growth rate is heterogenous across countries, reflecting the stringency of countries' accession procedures to the GATT/WTO.