Published by the American Geophysical Union as part of the Geodynamics Series, Volume 12. The decade of the 1970"s saw increasing global evidence leading to the reconstruction of the continents and oceanic plates through time, fostered by the Geodynamics Project. Aspects of this project are being continued under the auspices of the International Lithosphere Program, and in particular Working Group 2 of the Program, on Phanerozoic plate motions and orogenesis, is active in the unraveling of past continental distributions and the plate tectonic products of continental motions. Paleomagnetic techniques are especially useful for the determination of continental reconstructions, and this volume presents a number of papers dealing with syntheses, new interpretations of previous results, as well as new results for Paleozoic time.