At the beginning of the early modern period, the city of Seville was a bustling center of trade and commerce that connected the New World with the Old one. To control and monitor this traffic, the Spanish monarchy implemented a thorough bureaucracy and in Seville twenty-four notary offices were at the services of the numerous merchants from many parts of Europe, eager to participate in the auspicious Indies trade. This large amount of data allows the reconstruction of large networks of merchants who traded in Seville during that period. My investigations on this topic have focused on the foreign merchant communities in Seville and investigated first their relevance within the Indies trade, and second, the composition of the “foreigners” in the city. For that purpose, I have studied naturalization files, which can be considered a necessary requisite for foreigners to participate in the Indies trade, as well as notary files of selected offices between the years 1580 and 1640. In this paper I will outline my approach, my methods and, in particular, the specific value of applying social network analysis tools to the data to gain additional insights into the merchant communities’ social structures.