The main success and failure stories of international investor participation in infrastructure over the past decade are enumerated in a rich body of literature. A number of challenges for policy makers and businesses can be identified from this body of evidence, including pieces of supplementary analysis made available by the Investment Committee’s Secretariat, which were discussed with infrastructure specialists at an Expert Meeting on 3 March 2006. Some of the tentative lessons are summarised in this article. The success of infrastructure projects depends on the general political, regulatory and economic reality in which they are set. International investor participation in infrastructure should be seen as a long-term commitment to provide end-consumers in the host country with services. Government, in its capacity of a contracting party, acts as proxy for these consumers’ interests, and it partners with the private sector in delivering the services. Responsible business conduct is a key challenge for international investors participating in infrastructure. This is particularly in developing countries, where enabling environments tend to be less developed, and governments’ relative bargaining positions vis-à-vis international enterprises weaker.