W.M.(Terence) Gorman has been a major figure in the development of economies during the past forty years. His publications on separability, aggregation, duality and the modelling of consumer demand are recognized as fundamental contributions to economic theory. Many of his unpublished papers have achieved similar status as privately-circulated classics.This volume brings together for the first time all Gorman's important work, much of which has never been published before, on aggregation across commodities and agents, including separability, budgeting, representative agents, and the construction of capital and labour aggregates. Each chapter is preceded by an editorial introduction which describes its origin and place within the literature as well as the main results themselves. A forthcoming second volume, Modelling and Methodology, will cover topics on duality, demand, trade, and welfare.This book will appeal to academic economists interested in either specific aspects of Gorman's work or in the evolution of economic theory.