An approach is presented to determine the effect of travel time uncertainty and traffic information on mode choice in general and on the potential patronage of park-and-ride (P&R) facilities in particular. An expected-utility approach is applied to model the effect of travel time uncertainty and traffic information on the utility derived from the various travel modes. Through a series of simulations, the potential effects of travel time uncertainty and information provision on the use of a P&R facility in the Nijmegen region in the Netherlands are assessed. The simulations suggest that providing travelers with travel time information increases the patronage of P&R facilities because use of the car is avoided in the case of heavy congestion. However, the effect of information provision is limited when compared with other factors such as the quality of the P&R alternative in terms of travel time, facilities, and costs.