This paper demonstrates the important roles of feedstock and catalyst in determining the yield structure during fluid catalytic cracking (FCC) of bitumen-derived vacuum gas oils (VGOs). Three nonconventional VGOs, derived from Canadian oil-sands bitumen, were catalytically cracked in a fluid-bed microactivity test (MAT) reactor. Two commercial equilibrium catalysts were used: a bottoms-cracking catalyst containing rare earth exchanged Y zeolite (REY), and an octanebarrel catalyst containing rare earth ultrastable Y zeolite (REUSY) mixed with a small amount of ZSM-5. Both catalysts were embedded in active matrixes. Results indicated that the REY catalyst was more active, producing higher yields of valuable distillates and less coke for the same feed, whereas the catalyst containing REUSY/ZSM-5 gave more light gases and less gasoline (although the quality of this gasoline might be better). These results could be related to catalyst properties including zeolite type, rare earth content, matrix pore structure, zeolite-to-matrix ratio, and surface characteristics. The three feeds were ranked based on their yield structures, which could be explained through feed analyses, precursor concentrations determined by GC-MS, and product characterization data from a PIONA analyzer. MAT results were compared with riser pilot plant data at 55 and 65 wt % conversion. In general, at the same conversion, the difference in a given product yield from the two units could be maintained within 15%. Coke yield showed a greater disagreement, however, due to methodological differences in the analysis.