This article investigates the effect of the duration of membership in the General Agreement on Tariffs and Trade (GATT) and the World Trade Organization (WTO) on economic growth volatility. Using an unbalanced panel dataset of 153 countries over the period 1980-2019, the empirical analysis has revealed that the duration of membership in the GATT/WTO has been associated with lower economic growth volatility, with this negative effect being larger in member states that were subject to rigorous accession procedures than in other member states. More importantly, the membership duration has exerted a larger negative economic growth volatility effect in countries that further upgrade their export products. These findings complement the existing works on the strong positive effect of the membership in the GATT/WTO on economic growth, by shedding light on the importance of that membership (and notably the duration of the membership) for dampening economic growth volatility.