This paper studies political accountability under various contractual forms of Public Private Partnerships. A critical aspect of any ppp contract is the allocation of demand risk between the public authority and the private provider. We show that contracts in which the private provider bears demand risk motivate more the public authority from responding to customer needs. The policy implication is that the current trend towards a greater resort to contracts in which private providers do not bear demand risk may not be optimal in terms of allocative efficiency. Classification JEL : D23, H1, L5, 017.