AbstractWhile flexible exchange rates are commonly regarded as shock absorbers, heterodox views suggest that they can play a pro-cyclical role in emerging markets. This article provides theoretical and empirical support for this view. Drawing on post-Keynesian and structuralist theories, we propose a simple model in which flexible exchange rates in conjunction with external shocks become endogenous drivers of boom-bust cycles, once financial effects from foreign-currency debt are accounted for. We present empirical evidence for regular cycles in nominal US-dollar exchange rates in several emerging markets that are closely aligned with cycles in economic activity. An econometric analysis suggests the presence of a cyclical interaction mechanism between exchange rates and output, in line with the theoretical model, in Chile, South Africa, and partly the Philippines. Further evidence indicates that such exchange rate cycles cannot exclusively be attributed to external factors, such as commodity prices, US monetary policy or the global financial cycle. We therefore argue that exchange rate cycles in emerging markets are driven by the interplay of external shocks and endogenous cycle mechanisms.