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.

Australia’s National AI Plan makes strong commitments to infrastructure and adoption, but leaves governance and liability unresolved. This uncertainty exposes SMEs to risk, complicates investment decisions, and weakens public trust. History shows that technologies such as electricity became dependable only when standards, liability, and oversight aligned. AI now requires the same institutional attention if it is to move from experimentation to reliable national infrastructure

Policymakers, business strategists, innovation professionals, and researchers are increasingly being asked to invest in, create, or replicate innovation ecosystems. Until now, a clear framework for understanding what ecosystems are, how they function, and what enables their success has been largely missing, particularly in Australia. The Handbook of Innovation Ecosystems: Placemaking, Economics, Business, and Governance, just published by the Acton Institute for Innovation,