How can developing countries stimulate and sustain strong export growth? To answer this question, we examine 92 episodes of export surges, defined as significant increases in manufacturing export growth that are sustained for at least 7years. We find that export surges in developing countries tend to be preceded by a large real depreciation, which leaves the exchange rate significantly undervalued. In contrast, in developed countries, the role of the exchange rate is less pronounced. We examine why the exchange rate is important in developing countries and find that the depreciation is associated with a significant reallocation of resources in the export sector. In particular, depreciation stimulates entry into new export products and new markets. These new exports are important, accounting for over 40% of export growth on average during the surge in developing countries. We argue that a large real depreciation induces firms to expand the product and market space for exports.