Aggregating per capita gross domestic product growth across countries has always been a technical problem because of the complexities in the relative movements of exchange rates, economic output and populations. As such, the conventional approach to aggregating growth across countries suffers from sensitivity to exchange rates, as well as from the possibility of aggregate growth rates not being convex combinations of individual growth rates. This article introduces a new methodology in aggregating per capita growth rates that does not suffer from the drawbacks of the conventional approach. Using a welfare-based approach, it is shown that the proposed methodology is robust w.r.t. exchange rates and generates weights that always add up to unity, thus avoiding the anomalies that are inherent in the conventional approach. The methodology proposed in the article is applied to calculate aggregate growth rates of 33 developing member countries as well as five regional groupings, and the results are compared with those arising from the conventional approach. A number of insights arise that were previously hidden or inaccessible.