Abstract The use of cacao, in its familiar food and beverage form, dates back about 3,800 years. By the time of the discovery of America by Europeans, the Aztecs and Mayans had developed methods for drying, roasting and grinding cacao beans for use in beverages and foods. Today, the same processes are used, but have been adapted to modern machinery. The current study was conducted to compare the traditional Mesoamerican processing and modern processing methods and their impact on the antioxidant activity and flavan-3-ol content of the resulting processed cocoa mass. Two cocoa bean types were used: unfermented cocoa beans commonly produced and consumed today by the native peoples of Mesoamerica, and fermented Ivory Coast cocoa beans representing the most common country of origin for cocoa in the world today. Both bean types were processed by roasting and grinding using traditional and modern processing methods. The traditional method consisted of roasting whole beans on an earthenware comal heated with wood charcoal, de-shelling the beans, then grinding the beans to a paste using a stone metate and mano. The modern method consisted of roasting cocoa beans with pilot-scale equipment that simulates large-scale chocolate manufacturing using whole bean drum roasters, deshelling the beans followed by mechanical grinding using a ball mill producing a chocolate paste. The antioxidant capacity and flavanol content of these chocolate pastes were then determined. The data show that the antioxidant capacity and flavanol content of unprocessed Mexican Lavado cocoa beans were significantly higher than that of the unprocessed, fermented Ivory Coast cocoa beans. In unfermented Mexican Lavado cocoa beans, the traditional and modern processing revealed no clear advantage with respect to the antioxidant and flavanol contents. However, for fermented Ivory Coast beans, there were some differences in the level of flavanols between traditionally processed and modern processed fermented beans. These differences, while significant for some, but not all of the flavanol measures, were attributed to final roast temperatures achieved and to the possible lack of uniformity of bean fermentation.