3ie was set up to fill ‘the evaluation gap’, the lack of evidence about ‘what works in development’. Our founding document stated that 3ie will be issues-led, not methods led, seeking the best available method to answer the evaluation question at hand. We have remained true to this vision in that we have already funded close to 100 studies in over 30 countries around the world. And we strongly promote mixed methods, in which the attribution analysis of ‘what works’ is embedded in a larger evaluation framework combining process and impact evaluation, factual and counterfactual analysis.