Soil vapor extraction is a cost-effective technique for the removal of volatile organic compounds (VOCs) immobilized in the unsaturated zone. The design of soil vapor extraction system (SVES) requires determination of the number and locations of extraction wells and corresponding extraction rates. At present, few guidelines for design are available. Thus most designs are based on empirical assessments, simplified analytical approximations, or limited trial-and-error simulations. In this paper, three optimization-based design methodologies are introduced: (1) implicit enumeration, (2) systematic reduction, and (3) local search. These methodologies address the combinatorial nature of the design problem and properly evaluate the well interference effects in a multiwell system. Through a benchmark problem, a comparative evaluation of the three methodologies is made with regard to their solution accuracy, computational efficiency, optimality heuristic, and application limitations. ¿ American Geophysical Union 1996