FROM ITS LITTORAL margin to the open ocean, the westem South Atlantic (Fig. 1) is marked at all depths by circulation patterns and exchange processes that are centrally important to the region- al marine resources and local economies, and to the global flux of heat and dissolved substances. Among other important characteristics, the Southwest Atlantic (SWA) is characterized by the presence of the Brazil Current (BC), a warm west- ern boundary current that, while weaker than the Gulf Stream in terms of mass transport, is energet- ically comparable to its North Atlantic counterpart, particularly in the region of confluence with the northward-flowing Malvinas Current (MC) at approximately 38°S. Because of the wide range of issues needed to be understood in terms of the physical oceanography, this oceanic region has been addressed by several important scientific pro- grams, a few of which are listed in Table 1 and indicated on Fig. 2. Results from these and other programs are summarized here and recommenda- tions for future efforts are offered. Basic Patterns of Circulation Inshore from the northern Brazil Current, over a continental shelf that widens gradually toward the south, are regions where seasonal wind-driven upwelling of cold, nutrient-rich waters occurs. These are important elements of the shelf circula- tion and they have major impacts on biological productivity. In particular, the Cabo Frio region (Fig. 1) has long been known for its active wind- induced upwelling, and new measurements from surface drifters now show that a counter-circula- tion exists on the shelf in the Santos Bight inshore of the Brazil Current (Stevenson and de Souza, 1994). Occasionally, this may be associated with