This article discusses the choices, processes, and patterns that emerged during the first two decades of existence of networking technologies in two South American countries, Argentina and Brazil. Both nations stand out in the region for their implementation of science and technology development programs during the twentieth century. The Internet relies on many layers of infrastructure, technologies, and capacities; this work examines the commonalities and differences around its adoption in these national contexts. The essay combines an institutional analysis, which provides an understanding of the main processes that led to the establishment of the Internet in the two countries, with key concepts from the literature on technology appropriation. The tensions generated by new forms of networking due to the worldwide dissemination of TCP/IP are assessed in the framework of the paradigm shift in telecommunications reform during the 1990s.