The present chapter begins by studying the necessary minimum preconditions, in terms of elasticities and market shares, for successful cartel action. We then identify the markets where these preconditions appear to be fulfilled. There follows an account of the attempts of commodity producers to wieldmarket power for their own benefit, trying to answer questions such as: What were the triggers to the cartel action? How did it go? How did the buyers react? What prompted cartel disintegration? There is a heavy emphasis on oil, given the extraordinary price performance of this commodity.