<p>Development banks have expanded substantially worldwide. As of 2024, more than 544 development banks were operating in at least 155 countries and accounted for over 10% of global investment. Despite their prominence, their economic role remains controversial, in part because the literature provides little aggregate empirical evidence to discipline policy debates. This paper helps fill that gap through an analysis of the Brazilian Development Bank (BNDES), one of the world’s largest national development banks. First, we conduct a systematic review of 45 causal studies, showing that 79% report positive employment effects and 66% find higher investment. Second, we provide the first meta-analysis in the development bank literature, showing that BNDES lending increases employment in treated firms by 10% relative to the counterfactual. Third, we conduct a novel cost-effectiveness analysis of BNDES credit. Using fifteen alternative SVAR specifications, we estimate average investment additionality of R$0.89 per R$1 in BNDES loans. We then combine the aggregate additionality with administrative data on fiscal subsidies from a comprehensive dataset not previously examined in academic research. Between 2003 and 2023, the implied break-even additionality threshold is 0.19, well below both the average (0.55) and the median (0.46) of the available additionality estimates, including our own. Taken together, the evidence is consistent with the view that development banks can be effective instruments of development policy.</p>