This paper situates contemporary evaluations of the 'success' of Spain's Mondragon cooperative complex within a tradition of debate about the politics of economic transformation. It traces the long-standing suspicion of worker cooperatives among political and social analysts on the left, revisiting both the revolutionary and gradualist socialist critiques of cooperativism. Taking the set of problems identified by Beatrice and Sidney Webb as leading to the inevitable failure of producer cooperatives, the paper examines Mondragon for evidence of 'degeneration.' The ethical decisions made by Mondragon cooperators with respect to product, pay, profit, innovation, management, disputes and membership are discussed with a particular focus on the management of surplus production, appropriation and distribution. The paper calls for more sophisticated analyses of the economics of surplus distribution and the centrality of ethical debate to the construction of diverce economies and non-capitalist economic subject.