Option pricing, decision trees, and Monte Carlo simulations are three methods used to evaluate projects. In this paper, we compare their similarities and differences from three points of view-how they handle uncertainty in the values of key parameters, such as reserves, oil price, and costs; how they incorporate the time value of money; and whether they allow for managerial flexibility. We show that, despite their obvious differences, they are in fact different facets of a general project-evaluation framework that has the static base-case scenario as its simplest form. Compromises have to be made when modeling the complexity of the real world. These three approaches can be obtained from the general framework by focusing on certainty aspects.