Learning at Scale : Infrastructure, Aid Effectiveness, and World Bank Performance

This paper reexamines aid effectiveness using ex-post economic rates of return from 2,500 World Bank–financed infrastructure projects over six decades. Three facts emerge. First, average value creation is high: the mean economic rate of return is 24 percent (median 18.5 percent). Second, returns rise over time: after relative stability through the mid‑1980s, economic rates of return increased from the late 1980s onward, consistent with improved selection, design, and delivery. Third, economic rates of return are systematically higher in countries with weak institutions. In such countries, high-quality World Bank performance is associated with about a 12‑point increase in the average economic rate of return. A plausible mechanism is talent deployment. Higher‑quality task team leaders are disproportionately assigned to the most challenging contexts and linked to faster time‑to‑effectiveness and higher economic rates of return, despite longer, more intensive implementation. Overall, alongside country fundamentals, World Bank performance and talent deployment materially raise returns to scarce capital—especially where governance is weak.