The 3-D geologic model of the Western Canada Sedimentary Basin comprises 18 stacked intervals from the base of the Devonian Woodbend Group and age equivalent formations to ground surface; it includes an estimated thickness of eroded sediments based on 1-D burial history reconstructions for 33 wells across the study area. Each interval for the construction of the 3-D model was chosen on the basis of whether it is primarily composed of petroleum system elements of reservoir, hydrocarbon source, seal, overburden, or underburden strata, as well as the quality and areal distribution of well and other data. Preliminary results of the modeling support the following interpretations. Long-distance migration of hydrocarbons east of the Rocky Mountains is indicated by oil and gas accumulations in areas within which source rocks are thermally immature for oil and (or) gas. Petroleum systems in the basin are segmented by the northeast-trending Sweetgrass Arch; hydrocarbons west of the arch were from source rocks lying near or beneath the Rocky Mountains, whereas oil and gas east of the arch were sourced from the Williston Basin. Hydrocarbon generation and migration are primarily due to increased burial associated with the Laramide Orogeny. Hydrocarbon sources and migration were also influenced by the Lower Cretaceous sub-Mannville unconformity. In the Peace River Arch area of northern Alberta, Jurassic and older formations exhibit high-angle truncations against the unconformity. Potential Paleozoic though Mesozoic hydrocarbon source rocks are in contact with overlying Mannville Group reservoir facies. In contrast, in Saskatchewan and southern Alberta the contacts are parallel to sub-parallel, with the result that hydrocarbon source rocks are separated from the Mannville Group by seal-forming strata within the Jurassic. Vertical and lateral movement of hydrocarbons along the faults in the Rocky Mountains deformed belt probably also resulted in mixing of oil and gas from numerous source rocks in Alberta.