The focus of this chapter is the extended sociopolitical and cultural networks, predominantly female, that the Grand Duchess Vittoria developed throughout Italy and Europe. The first part of the chapter will highlight how women in power relied on each other and mediated with other important figures to develop their patronage, and how they exercised their power in tandem. To this end, examples of correspondence and petitions exchanged between Vittoria and her female kin will be examined, revealing the authoritative and efficacious agency of the Grand Duchess. The second part will examine her female networks, again through letters but also account books and inventories, identifying the key figures with whom she developed strong and lasting affective and diplomatic relationships, not only on the peninsula but also in France, Austria, Poland and Spain. Such relationships and alliances were sustained by this epistolary network and reinforced through gift exchange.