This book began, more than a dozen years ago, as a joint venture into the understanding of the course of philosophic thought in America. In 1963 we published a brief preliminary volume for the Union Panamericana entitled Principales Tendencias de la Filosofia Norteamericana. Since that bantling appeared, our enterprise has progressed through an unbelievably perilous and circuitous route to its present form, helped on at critical junctures by the kindness of a variety of Samaritans. Although we have both contributed to every chapter, each author bears a primary responsibility for some chapters. Elizabeth Flowers bears primary responsibility for chapters 4, 5, 6, 8, 11, 14, and 15; Murray Murphey is chiefly responsible for chapters 1, 2, 3, 7, 9, 10, and 12. Chapter 13 was a joint product.