Doug Irwin and Peter Temin offer a welcome study of the tariff and American industrialization. Although largely overlooked, the tariff significantly influences our interpretation of early American industrialization. If the tariff had no substantial effect, as Irwin and Temin argue, we view early American industrialization quite differently than if the tariff induced industrialization by diverting trade to otherwise noncompetitive firms within a customs union, as I believe. Although I welcome attention to the tariff, I feel that Irwin and Temin's argument rests on a misconception of the British cotton industry and of the nature of potential competition between American and British cloth in the absence of protection.