Reformation and Counter-Reformation networks organized by Catholic women and men grew rapidly during the Counter-Reformation, key contributors in the task of reforming, initiating, or implanting Catholic religious practices throughout Europe and in European colonies. Spurred by anti-Protestantism as much as by the need to recover ground lost to anti-Catholic forces, networks evolved quickly in areas torn by religious wars, such as France and the Spanish Netherlands. During the same period, Catholic countries on the Continent accepted and fostered networks of co-confessionalist refugees coming in large part from England and Ireland. Such networks were essential to global reform; their survival serves as a marker of Counter-Reformation success. Another marker was the introduction or expansion of religious orders, particularly female orders, and the recovery or development of charitable institutions. Within formerly Catholic areas now under Protestant control, the preservation of Catholic religious practice required secret or semi-secret networks to provide material support and religious guidance. Since the identities of people in these networks also needed protection, activity patterns have emerged slowly. While this is not yet a quantitative study, therefore, three loosely interrelated categories are discussed: religious orders as networks, laywomen’s networks, and clandestine networks. These networks generally communicated through manuscript and printed texts that were produced for or circulated among network members. Certain categories of text, such as circular letters transmitted between convents, supported the development of communal identities among networks formed between convents of specific orders.