The southwestern Atlantic Ocean margin (SWAOM), along the coasts of southern Brazil, Uruguay, and Argentina, is one of the most productive regions of the world ocean and is believed to be the largest carbon dioxide (CO2) sink in the Atlantic Ocean. The region is dominated by two major boundary currents (the Brazil and the Malvinas), which impinge on a broad continental shelf along southeastern South America and converge offshore of the Rio de la Plata, the largest source of freshwater to the South Atlantic Ocean. Scientific knowledge about this region is based on past research focused generally on processes within the confines of the waters of the individual countries and from single disciplines. However, the complex interactions of physical, chemical, and biological processes that control the transport and production in time and space across this region require multidisciplinary investigation and international cooperation. This led a group of more than 40 marine scientists from these countries and the United States to convene a workshop to review what is known about this region, to suggest how future multidisciplinary research might be organized, and to foster regional and North-South scientific cooperation.