The city planning theories of Le Corbusier have been well attended and his realizations widely published, but his style of presentation coupled with a general lack of systematic study on the part of his audience has resulted in some misunderstanding of his work. This thesis is an attempt to clarify the basic principles of planning as expressed by Le Corbusier and to evaluate them in reference to the conceptual development of planning. He has been an eminent theorist and creative artist for over four decades, and the fact that he is still active makes a definitive study impossible. This thesis in no way purports to be that. The thesis is organized into three parts: an introduction including a biographical sketch of his early years; a clarification of principles as shown in his writings and manifested in his projects; and a commentary on the significance of his ideas in the field of planning. Chronological order is generally followed to help emphasize the evolution of his thought. It is outside the scope of this thesis to analyze historical precedents of Le Corbusier's thinking, and it has already been done in a general way in the histories by. Gideon, Whittick and others, although there is still a great need for the scientific historian to apply his methods to the field of planning.