This paper studies the relationships between the choice of a sourcing mode for information systems, the value of the resources used in systems development activities and the presence of those resources at sufficient level within the firm. The objective is to better understand the factors underlying the decision to keep the development of an information system inside the firm or to entrust it to an outside partner. A sourcing model is proposed using the resource-based theory. Two case studies drawn from a larger study are used to illustrate the concepts used in the research model. Data from these two projects illustrate how the model could be used to predict the sourcing mode retained by the managers for each project, given the availability of the necessary resources and the strategic value of the future system.