These papers, by a number of leading international-trade theorists, present the first significant theoretical work to be done on a topic of considerable interest, import competition. Nine theoretical papers, on topics ranging from protectionist lobbying to adjustment costs, are synthesized in the editor’s Introduction, which also contrasts these contributions with the traditional classroom analysis of import competition. Three major empirical studies close the volume. It will prove indispensable for anyone who wishes to think clearly about import competition and about how economies do-and should-respond to it.