Volume 1. History of the Congress, Scientific Plan of the Congress, Philosophy, Mathematics. Volume 2. Political and Economic History, History of Law, History of Religion. Volume 3. History of Language, History of Literature, History of Art. Volume 4. Physics, Chemistry, Astronomy, Sciences of the Earth. Volume 5. Biology, Anthropology, Psychology, Sociology. Volume 6. Medicine, Technology. Volume 7. Economics, Politics, Jurisprudence, Social Science. Volume 8. Education, Religion. The details and specifications of the volumes were prepared for competitive bids and submitted to twelve of the prominent publishers of the country. The most advantageous bid was received from Houghton, Mifflin & Company of Boston, Mass., and was accepted by the Exposition Company. The Administrative Board and the authorities Of the Exposition feel deeply pleased at the result, inasmuch as the imprint of this firm guarantees a work in full accord with the high plane upon which the Congress has been conducted. It was determined to print the entire proceedings in the English language, inasmuch as the Congress was held in an English-speaking country and the vast majority of the papers were read in that language. The consent of every foreign speaker was obtained for this procedure. It was found, after collecting, that the number of addresses to be translated was forty-four. The translators were selected by the editor upon the advice of the members of the Administrative Board and Organizing Committee, and great care was taken to find persons not only thoroughly trained in the two languages and possessing a good English style, but also persons who were thoroughly conversant with the subject on which the paper treated. Many of the translators were suggested by the foreign speakers themselves. As a result of this careful selection, the editor feels confident that the original value of the papers has been in no wise detracted from, and that both in form and content the translations are thoroughly satisfactory. It will be found that some addresses are not closely related to the scheme of the Congress. Either through some misunderstanding of the exact purpose of the Congress, or through too close devotion to their own particular phase of investigation, some half-dozen speakers submitted papers dealing with special lines of work. These, while valuable and scholarly from their standpoint, do not accord with a series of papers prepared with a view to general relations and historical perspective. The exceptions are so few, however, as not seriously to interfere with the unity of the plan.