Résumé : This paper shows that the creation of an independent regulatory agency (IRA) is often not a necessary or sufficient condition to help countries attract private participation in the operation and financing of the water and sanitation sector of developing countries. The odds of an impact are, however, significantly higher for Latin American and Caribbean countries and to a lesser extent Eastern European countries, than for any other region. Higher income levels and higher prices are also correlated with a higher effectiveness of IRAs in attracting private sector financing. The analysis of the impact on the various types of PPP contracts shows that, at the margin, IRAs are irrelevant in general, to the contract choice, except for greenfield projects for which IRAs may be counterproductive at the margin.