In recent years, flexibility has emerged as a divisive issue in discussions about the appropriate design of processes for making software. Partisans in both research and practice argue for and against plan-based (allegedly inflexible) and agile (allegedly too flexible) approaches. The stakes in this debate are high; questions raised about plan-based approaches undermine longstanding claims that those approaches, when realized, represent maturity of practice. In this commentary, we call for research programs that will move beyond partisan disagreement to a more nuanced discussion, one that takes into account both benefits and costs of flexibility Key to such programs will be the development of a robust contingency framework for deciding when (in what conditions) plan-based and agile methods should be used. We develop a basic contingency framework in this paper, one that models the benefit/cost economics described in narratives about the transition from craft to industrial production of physical products. We use this framework to demonstrate the power of even a simple model to help us accomplish three objectives: (1) to refocus discussions about the appropriate design of software development processes, concentrating on when to use particular approaches and how they might be usefully combined; (2) to suggest and guide a trajectory of research that can support and enrich this discussion; and (3) to suggest a technology-based explanation for the emergence of agile development at this point in history. Although we are not the first to argue in favor of a contingency perspective, we show that there remain many opportunities for information systems (IS) research to have a major impact on practice in this area.