Our paper is motivated by one simple question: Why do so many action research efforts fail to persist over time? We approach this question, the problem of sustainability, building on a perspective on action research identifying the pivotal importance of networks. More precisely, local action research interventions need to be conceptualized and approached as but one element in a larger network of action in order to ensure sustainability. A vital aspect of our perspective is that local interventions depend heavily on the support of similar action research efforts in other locations. This is essential for the necessary processes of learning and experience sharing. We suggest that the scaling (i.e., spreading) of the intervention is a prerequisite, not a luxury, for sustainable action research. Empirically, we base our analysis on an ongoing, large-scale action research project within the health care sector (called HISP) in a number of developing countries. HISP provides a fruitful occasion to investigate key criteria for our approach to action research, namely sustainability, scalability, and capacity to be politically relevant to the participants. We contribute to three discourses: (1) models of action research, (2) lessons for health information systems in developing countries, and (3) more generally, IS implementations that are dispersed, large-scale, and have scarce resources.