To resolve the problem of design marginalization in organizations, we introduce the concept of institution and an Aristotelian framework for human activity to identify an action-based approach for design in complex systems. When design is positioned solely as an activity of production—despite the success of human-centered products—it misses an opportunity to influence institutions, or the human-side of organizations. When repositioned as a practice of shaping action, design engages in the ordering, modifying and reordering of social structures, environments and culture. In short, a theory of institution provides a human-centered approach to systems design and organizational transformation.