Initiatives that seek to realize the vision of nation-wide information infrastructures (II) in healthcare have often failed to achieve their goals. In this paper, we focus on approaches used to plan, conduct, and manage the realization of such visions. Our empirical material describes two Danish initiatives, where a national project failed to deliver interoperable Electronic Patient Record (EPR) systems while a small, local solution grew and now offers a nation-wide solution for sharing patient record information. We apply II theory, specifically the five design principles proposed by Hanseth and Lyytinen, to contrast the organization and implementation strategies of the two projects. Our findings highlight how implementation strategies differ with respect to how stakeholders are mobilized. We argue that the realization of nation-wide IIs for healthcare not only requires a gradual transition of the installed base, which current II theory advocates. Here we articulate and exemplify a modular implementation strategy as an approach that also addresses the challenges related to mobilization and organization of multiple stakeholders.