An optimal control problem of dynamic pricing is studied. In the model, prices are chosen to sell multiple products to multiple customer classes over time. The products share a number of scarce resources. All parameters, such as the arrival rates of customers, their purchasing probabilities, their cancellation rates, and the cancellation refunds, are allowed to be time dependent. A solution method for the problem is developed, and is tested with some numerical examples. # Supported, in part, by the National Science Foundation under grant DMI-9875400. 1