Feedstock quality affects the fluid catalytic cracking (FCC) process to such an extent that even the operating variables or the catalyst selection seem to be of secondary importance. This paper focuses on the way that the bulk properties of an FCC feedstock can explain the extent of catalytic reactions (crackability) and coke production (coking tendency). The final goal of this effort is to develop a model for the characterization of fluid catalytic cracking feedstocks on the basis of standard analytical procedures accessible to the average refinery. Using different approaches to the characterization of petroleum fractions, a model was developed for the prediction of the behavior of fluid catalytic cracking feedstocks under real FCC conditions. A large database of experiments, performed in the FCC pilot plant of the Chemical Process Engineering Research Institute (Thessaloniki, Greece), was used for the development of the feedstock characterization procedure. The aromatic carbon, the average carbon number, and the total nitrogen and sulfur contents were appropriately combined to predict the effect of feedstock quality on the conversion and coke yield of the fluid catalytic cracking process. The simulation results reveal the ability of this approach to predict accurately the crackability and coking tendency of an FCC feedstock from easily measured properties and to explain the impact of these properties on the FCC outcome.