This paper presents a new methodology involving the use of genetic algorithms for the selection of cutting conditions in single-pass milling operations based on a comprehensive optimization criterion integrating the contributing effects of all major machining performance measures. A Web-based, user-interactive expert system has been established for the application of the newly developed methodology to enable process planners to determine optimum cutting conditions in milling operations. Case studies are presented to demonstrate the application of this new methodology for the determination of optimum cutting conditions in face- and end-milling operations.