This paper proposes a framework to analyze open economies with realistic patterns of currency use in exporter invoicing. We provide sufficient statistics for changes in macroeconomic aggregates in response to exchange rate shocks involving sales shares, currency invoicing, markups, and pass-through. Using administrative data covering the universe of French firm-level trade from 2011 to 2019, we document that large firms are the ones using foreign currencies to trade, and that foreign currency invoicing is associated with higher markups. We calibrate our model to the data and isolate the importance of firm heterogeneity by comparing our model to one with a representative firm. We find that firm heterogeneity has a large impact on changes in aggregate productivity following exchange rate shocks, and a modest impact on changes in aggregate prices.