This book examines alternative methods for achieving optimality without all the apparatus of economic planning (such as information retrieval, computation of solutions, and separate implementation systems), or a vain reliance on sufficiently 'perfect' competition. All rely entirely on the self-interest of economic agents and voluntary contract. The author considers methods involving feedback iterative controls which require the prior selection of a 'criterion function', but no prior calculation of optimal quantities. The target is adjusted as the results for each step become data for the criterion function. Implementation is built in by the incentive structure, and all controls rely on consistency with the self-interest of individuals. The applicability of all the methods is shown to be independent of the form of ownership of enterprises: examples are given for industries which are wholly privately owned, wholly nationalised, mixed, and labour-managed.