This book draws on the files contained in numerous archives with a view to transposing for the first time the study of the political use of patronage and clientele relations and social networks (micropolitics) from internal power structures in early modern polities to the relations of those polities with other states. The central focus is on the wide-ranging interaction between the Roman curia of Pope Paul V. (1605-1621) and his family, on the one hand, and Spain (including Naples and Milan) and the financial centre Genoa, closely associated with Spain, on the other.