Comparison of the amounts of inorganic and organic carbon in Miocene-Pleistocene sediments from ODP Sites 1081, 1082, 1084, 1085, and 1087 and DSDP Site 532 on the margin of southwest Africa provides insights into the evolution and oscillations of enhanced paleoproductivity associated with the Benguela Current upwelling system. Concentrations of CaCO3, which record coccolith production in this system, are consistently ~75 wt% at Sites 1085 and 1087 in the Cape Basin. In contrast, concentrations in sediments near the Pliocene/Pleistocene boundary drop to 25 wt% at Sites 532, 1082, and 1084 in Walvis Basin and on Walvis Ridge because of greater opal production at these areas during this period. Organic matter is predominantly marine in origin at all locations; its accumulation started to increase in the late Miocene and peaked in the early Pleistocene. TOC concentrations range between 0.1 and 18 wt% and are highest in sediments deposited at Site 1084 in Walvis Basin. TOC concentrations are especially elevated in dark parts of prominent light-dark color alternations that record varying combinations of elevated productivity, downslope transport of organic carbon-rich sediments from the shelf edge, and dissolution of CaCO3 in the seafloor. Both the production and preservation of organic matter appear to have fluctuated regularly during the evolution of this upwelling system. Moreover, the correspondence of higher Rock-Eval hydrogen index values, higher elemental C/N ratios, and higher TOC concentrations suggests that the rate of export production and the degree of preservation of marine organic matter in bottom sediments are related and have increased since the Miocene.