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. A case study is used to illustrate the concepts used in the research model. Data from this case illustrate how the model could be used to predict the appropriate sourcing mode, given the availability of the necessary resources and their strategic value.