The 12th- and 13th-century early Gothic churches from the region around Paris which form the basis of this study were large-scale undertakings. Dr James draws on evidence which suggests that work proceeded in a series of projects, when funding, technical problems (for example, slow-setting mortar), and the work of other trades (such as roofing and centring) allowed. Within each project there were generally a number of separately organised phases, or `campaigns', and it is from close study of these campaigns that the author proceeds to an identification of the characteristics of the individual master masons, the template-makers.