Many countries offer government-backed export credit guarantees to domestic firms. We investigate the effects of such guarantees on firm exports, jobs and value added. Using uniquely detailed and exhaustive transaction-level panel data on guarantees and granular information on trade, exporters and foreign buyers, we perform difference-indifferences matching estimations. We find that guarantees improve firm performance. However, the effects are strikingly heterogeneous across firm size and response variables. Using guarantees increases the firm-destination probability of exporting and the value of exports by 18 and 172 percent, respectively, but does not generally increase jobs or value added. Smaller firms benefit the most in terms of exports. Overall, the evidence suggests a causal link from guarantees to firm export performance.