Why does the same technology lift productivity in some places and disappoint in others? The complementarity thesis explains the gap: returns depend on what technology is combined with. Applied to innovation districts, value comes from complements across placemaking, economics, business, and governance, underpinned by infrastructure. Leadership, collaboration, and learning mindsets become practical policy levers, not soft extras.

This article reviews The Handbook of Innovation Ecosystems , detailing its "four-domain convergence framework" . It argues that successful ecosystems are not accidental but require the deliberate, long-term integration of Placemaking, Economics, Business, and Governance . It provides a practical guide for policymakers and practitioners to move beyond rhetoric and build durable, inclusive innovation capacity .