This paper investigates how productivity influences firms' exports.Various finn characteristics are employed to test the self-selection hypothesis alongside the effects of firms' productivity on their share of exports in total sales.Using a pseudo-panel data set constructed from the firm-level data for the manufacturing sector in Nigeria,we find no evidence that higher productivity influences the decision on whether or not a firm would participate in exports.However,it is established that higher productivity increases the share of exports in total sales of firms that are already participating in foreign markets.A policy implication of our result is that Nigeria can realize a larger share of manufactured exports in total merchandise exports by directing efforts towards improving primarily the productivity of firms that are already involved in exports.