This paper looks at the empirical role of exchange rate hysteresis in affecting the responsiveness of export supply to exchange rate changes and measures its quantitative importance by breaking down export adjustments between changes in output levels by existing exporters (intensive margin) and movements due to changes in the number of exporters (extensive margin). Using data on a representative sample of Spanish manufacturing firms, the paper finds sunk costs hysteresis to be an important factor in determining export market participation, but unrelated to exchange rate uncertainty. Finally, although hysteresis exists, its effect on the responsiveness of aggregate trade volumes to exchange rate changes is quantitatively small. A 10 percent home currency depreciation results in an increases in export volume due to the increase in the number of exporting firms of only .8% of export volume.