In 2016 a group of innovators from healthcare, mental healthcare, social work and design teamed up to create a roadmap to a future-proof (health)care system. An important part of this healthcare system is an open source ecosystem of digital health applications that can cooperate in an integrated way. Right from the start, privacy has been an important part of the project: agency is at the core of the innovation project and agency is among the central values within privacy. So one of the central questions of the project was: “How to translate the principle of agency into design choices for data privacy within an ecosystem of digital health applications.” We will tell how this question was answered by looking back at the process and at the choices made about the user interaction and technology. During this project we were confronted with three separate perspectives on privacy: a theoretical perspective that is generally focused on the philosophical meaning of privacy, secondly, a technological perspective driven by the suppliers of digital products and lastly a user interaction perspective, driven by the end user’s experience of privacy. The conflicting perspectives were holding back the progress of the project. Therefore we had to find a way to mediate between these separate perspectives. An important part of this mediation process was finding common values and translating these to overarching principles that are comprehensible to the different perspectives and stakeholders. Next these newfound principles were validated with end-users, representing the interaction perspective. For this purpose we used gamification and mock-ups to make the more abstract principles tangible and testable. Finally the general principles were translated to clear design guidelines for the technological perspective. This presentation will show how we combined a theoretical view on privacy with the users perspective and how we translated these into guidelines for user interaction and into a technical architecture. And you will leave with some practical tips when conducting comparable projects!