Abstract: A subset test module and associated methodology for utilizing the same are disclosed that facilitate identification of process drift in semiconductor fabrication processing. A test wafer having a plurality of die formed thereon has a plurality of test modules formed within the die. The plurality of test modules are substantially the same from die to die, and the respective modules similarly include a plurality of test structures that are substantially the same from module to module. Corresponding test structures within respective modules on different die are inspected and compared to one another to find structures that are sensitive to process drift. One or more structures that experience differences from module to module on different die are utilized to develop one or more test modules that can be selectively located within production wafers and monitored to determine whether process drift and/or one or more other aberrant processing conditions are occurring.