Information infrastructures of businesses and government are increasingly interwoven and highly dependent on each other. Though often referred to as sociotechnical innovations, the development of these information infrastructures often has a technological focus. The related and even concurrent development of new social practices is understudied. As a result, the social innovation taking place next to the development of large-scale information infrastructures is ill understood. To address this gap, we study public-private information infrastructure developments at three layers and over a prolonged period of time and focus on the innovation in the social practices. Our goal is to understand the social innovation that is taking place within and among these layers and within their technological context. A finding was that stakeholders face changes in their existing practices and have to alter them as a pre-condition to realize the benefits that information infrastructures promise to provide. New social practices need to be developed and sustaining the innovation requires the development of governance mechanisms.