A number of studies have addressed issues relating to the physiological, environmental and economic values of trees in cocoa farming systems. However, to date, little has been done to quantitatively examine the effect of crop diversity on cocoa farming efficiency. This study therefore sets out to first investigate whether and to what extent crop diversity (defined as the mixing of cocoa with other crop species on farmers' plots) affects productivity on cocoa farms. Secondly, it sought to establish whether there are economies of scope (i.e., cost complementarities) from the sharing of farm inputs by crops on the same plots. Our results indicate that diversified (i.e., multi-crop) cocoa farms are more efficient than single (i.e., mono) crop farms. Furthermore, our estimate for the economies of scope parameter indicates possibilities for cost complementarities between production of cocoa and other crops on the same plot. We advocate further investigation on the issue of scope economies to determine which crop combinations offer better cost complementarities and also meet biodiversity conservation objectives.