The paper suggests that research on the role of mobile telephony for socioeconomic development (M4D) draws on two frames. One frame stresses the relative freedom of telephone users to do whatever they choose. The other stresses how technologies and technology-led interventions are embedded in recursive, context specific relationships with user communities. Together these frames support M4D’s “dual heritage”. After detailing current M4D archetypes representing each heritage, the paper introduces a conceptual and practical synthesis, that is, large-scale platforms for distributed, semi-constrained interaction. This paper considers two examples of such platforms – MXit, South Africa’s mobile social networking service, and M-PESA, Kenya’s mobile money transfer system – including both anticipated and unanticipated consequences of operating “at scale” and beyond the confines of a controlled M4D intervention. Finally, this paper introduces implications of the dual heritage and of the rise of hybrid platforms for research and practice.