Contemporary understanding of information systems (IS) is flawed by fundamental problems in information systems research and practice. In this chapter, we claim that philosophical presuppositions have a great influence on our understanding of IS. Reflecting on the modernism-postmodernism debate and its methodological consequences for IS research, we derive the need for a paradigmatic foundation of IS research. Referring to Kuhn’s concept of “paradigm,” we develop a framework for the conceptualization of “paradigms of inquiry.” We use the notion of “model,” which we believe to be pivotal for the understanding of IS, to illustrate the implications of the adoption of a “paradigm of inquiry.” In response to a criticism of both the positivist and the radical-constructivist paradigms, we develop a paradigm called “sociopragmatic constructivism” (SPC). Presupposing that human inquiry relies on social contextualization, common practice and cultural history, we propose an agenda for upcoming IS research grounded in SPC.