This second part of the book - Formations et Emplois qualifiés. Les transformations dans le bâtiment en France et au Royaume-Uni - focuses the analysis of the dynamics of companies in order to understand their investment in training. In France it seems "natural" that on the job training takes place in small businesses with large firms having little to do with it, when it is not the case in the UK. Why is it so? Beyond the answer to this fundamental question, the second part of this book also highlights an emerging type of productive organization based on cascading subcontracting, by which growing by shrinking is the core pattern of the leading firms: their market shares expand whilst their direct labour force shrinks.