The existing CGE (computational general equilibrium) models can be divided into three broad categories. The first category of models (of which the standard GTAP(General Trade Analysis Project) model is a classic example) emphasizes the static effects of policy related to general equilibrium resource reallocation. The second class of models incorporates scale economies and imperfect competition. These extensions not only emphasize resource reallocation effect but also pro-competitive effects. Most recently, a third class of models that include classic and new-growth related accumulation effects has emerged. However, the second and the third class of models are still in the initial GTAP development stages. Based on several GTAP technical papers and literature survey, this seminar presents techniques for the incorporation of several stylized representations of scale economies and imperfect competition into the GTAP modeling framework. The theoretical foundation for imperfect competition and potential model applications will also be discussed.