High-speed trains can compete successfully with road, air and conventional rail services on densely trafficked routes where willingness to pay is sufficient at the relatively elevated fare levels needed to cover costs. High-speed rail investments can also relieve congestion on the conventional rail network, and the capacity for high-speed rail to provide fast city centre to city centre services creates new possibilities for day-return business trips and short-stay leisure trips. The long cost recovery periods for high-speed lines imply government involvement in the financing of most investments. The high costs mean that governments can be exposed to accumulation of large debts, particularly if demand develops more slowly than expected. Where high-speed rail investments are designed to promote regional integration rather than meet commercial demand, significant subsidy from central and regional governments will be needed for the construction of infrastructure and possibly also for train operations. This report examines the key factors that drive the costs of high-speed rail investment and reviews the economic benefits delivered by high-speed rail services on the basis of experience in countries that have developed large high-speed rail networks.