Using a library of machine modules, modular machine tools are being developed by many machine tool manufacturers to reduce design lead time. To accommodate frequent changes in product design in a timely and cost-effective manner, the next generation of machine tools should be reconfigurable to process a family of products. This enables reduction not only in machine design lead time but more significantly a reduction in machine set-up and ramp-up time. The essential characteristics of Reconfigurable Machine Tools (RMTs) include modularity, convertibility, flexibility, and cost-effectiveness. Currently there is no systematic method of designing modular machines, let alone reconfigurable machines. This paper presents a methodology for kinematic synthesis of machine tools using screw theory. The motion characteristics of a set of desired machining tasks as well as stored library of machine modules are captured in a common representation scheme. A simple design example to illustrate the application of this methodology for systematic selection and synthesis of reconfigurable machine tools is presented. The proposed methodology can be extended to include the dynamic characteristics and control schemes to enable integrated design of machines and controllers.