In an increasingly digital world, introducing new interorganizational systems requires establishing associations and relying on contributions of multiple actors that control existing technical solutions. This article examines the question: “how can large-scale system implementations across multiple organizations be governed in situations of distributed control over components?”. To answer this question, we present the findings of a longitudinal case study on the introduction of e-prescription in Norway over a 14-year period. The findings point to complementary architectural and managerial arrangements that make possible a polycentric governance approach. This work contributes to research on Information Systems Governance by providing insights relevant to mandating large-scale system implementations across organizations by mobilizing and orienting multiple contributors that control various pre-existing solutions.