Around the world, growth has yet to recover to its pre-Global Crisis trend. This column uses the crisis as a quasi-natural experiment to test the endogenous growth hypothesis, which suggests that output has not recovered because the crisis affected the rate of technological progress. Firms that preferred a bank that was more severely affected by the crisis experienced a large fall in R&D investment and a persistent fall in output in subsequent years. This suggests a direct link between R&D and future productivity, as predicted by endogenous growth models.