Over the past decade most developingeconomies have involved the private sector in providinginfrastructure services. Indeed, between 1990 and 2002, 136low- and middle-income countries introduced privateparticipation in infrastructure sectors-65 of them in atleast three sectors. During that period the private sectortook over the operating or construction risk, or both, formore than 2,600 astructure projects in developing countries,attracting investment commitments of more than US$800billion. These projects have been implemented under schemesranging from management contracts to concessions todivestitures to greenfield build-operate-transfer orbuild-operate-own projects. Annual investment flows toinfrastructure projects with private participation grewstrongly between 1990 and 1997, from US$18 billion to morethan US$127 billion. Since then investment flows havegradually declined, except for a temporary recovery in 2000.