The paper presents a methodology to construct a Discrete Event Simulation model to assess the expansion of a container terminal. The methodology was applied to the Ensenada International Terminal located in Mexico. The simulation integrates all the operations of the container terminal including the arrival of vessels, trucks, and storage of containers. The expansion plan included the addition of anew berth, and additional storage yard space. The expansion model was evaluated under different demand increments. Recommendations were provided on the level of demand that the expansion may be able to serve. As a result, the additional berth will increase the capacity, but the projected storage space will support up to a 140% increase in demand with a 20% in reserve. The terminal must consider additional storage space either in the terminal or at an external facility for additional demand greater than 140%, or for having a larger storage reserve.