We assess the empirical relevance of the new theory of regulation, using a principal-agent frame-work to study the regulatory schemes used in the French urban transport industry. Taking the current regulatory schemes as given, the model of supply and demand provides estimates for the firms ’ inefficiency, the effort of managers, and the cost of public funds. It allows us to derive the first-best and second-best regulatory policies for each network and compare them with the actual situation in terms of welfare loss or gain. Fixed-price policies lie between fully informed and uninformed second-best schemes. Cost-plus contracts are dominated by any type of second-best contract. From these results, we may conjecture that fixed-price contracts c...