The Salviati Archive of the Pisa Scuola Normale Speriore is the most complete archive for trade and industry in the late medieval and Early modern period. The ENPRESA project is aimed to study norms, pratices and the network structures, using firm records to highlight early modern European economy. The Salviati Archive preserves for its most past part trade companies and industrial (ie textile) production firms records. Investigating these document is the best way to go beyond the current descriptive or institutionnalist approach and reach the field of choices and network dynamics. Firm account-books are an extremely precise and reliable historical sources. Yet, it is difficult to link the huge quantity of information they provide to the general economic context, which is the actual target of the investigation. The core of the research will therefore be a cross examination on individual strategies and firm dynamics,