This Handbook provides a forward-looking view on how quality infrastructure investment can be implemented to deliver on key policy priorities, notably catalysing the low-carbon transition, safeguarding biodiversity, building resilience, addressing regional disparities, and underpinning sustainable development. The Handbook assesses some of the infrastructure investment needs required to deliver on these priorities, identifies challenges and bottlenecks, and proposes solutions. It highlights effective infrastructure governance, the mobilisation of financial resources, and the subnational dimension of infrastructure governance and investment as key means for delivering quality infrastructure investment.