The neighbourhood concept is arguably one of the major planning landmarks that shaped the urban form of the twentieth century city in many countries. Coincidently, both the neighbourhood idea of Clarence Stein and Henry Wright, exemplified in their plan for Radburn, and the Neighbourhood Unit idea of Clarence Perry were published in 1929. The urban design principles of Stein and Wright included the idea of a superblock of residential units grouped around a central green, the separation of vehicles and pedestrians, and a road hierarchy with culs-de-sac for local access roads. A cluster of superblocks was to form a self-contained neighbourhood. A group of neighbourhoods would then comprise the city. For Perry the physical arrangement of the elementary school, small parks and playgrounds, and local shops was the basis of his neighbourhood idea. Each neighbourhood was to be a >unit= of the city. Briefly outlined are the deviations from the original ideas made subsequently by numerous architects, planners, developers, and bureaucrats. This article re-examines the intentions of Stein and Wright and Perry and the sources of their ideas to recover the principles of the original concepts that have become obscured over the decades