This description of the Structure-Mapping Engine (SME), a flexible, cognitive simulation program for studying analogical processing which is based on Gentner's Structure-Mapping theory of analogy, points out that the SME provides a "tool kit" for constructing matching algorithms consistent with this theory. This report provides: (1) a review of the Structure-Mapping Theory; (2) a description of the design of the engine, including representation conventions, an overview of the computations performed by the algorithm, and analyses of these computations; (3) examples of the application of the SME to various analogies, including the Rutherford Atom Analogy, the PHINEAS system for discovering heat flow, and in modelling human analogical processing; (4) a comparison of the SME with other work in artificial intelligence and psychology; and (5) a discussion of the implications of the project and plans for future work in cognitive simulation and machine learning studies. Sixty-six references are listed and two appendices provide additional explanations of the three types of rule sets used by the SME and sample domain descriptions given to the SME for the described examples. (RP)