Leading specialists in international trade theory were asked to write on a new and different topic. Some responded by developing an idea that they had toyed with but never quite put together. Others offered a new and distinctive approach to an established topic. To respond to these adventurous and pioneering pieces, other eminent trade theorists prepared comments on each of the individual papers. Paul A. Samuelson wrote the keynote for the volume reflecting on the past and looking to the future of international trade theory.