The purpose of this article is to explore Marshall's perspective on the changes of size and organisation of firms in his time and, more generally, the environment of monopolistic tendencies. It examines the Marshallian evolutionary approach to business organisation as already presented in his Principles of Economics and identifies the quality of this approach as responsible for the keen perceptions made in Industry and Trade, the book in which business organisation and monopolistic tendencies are investigated. The consideration of Industry and Trade includes a comparison that identifies similarities between propositions about big business by Marshall and Alfred Chandler, the author whose work stands as the paradigm for the study of the genesis and development of big business. As an exploration of Industry and Trade, this article contributes to the assessment of a still very little studied book and draws attention to Marshall's method of combining theory and history.