Although difficult to define, stimulability is an easily measured skill that can provide valuable information for clinicians treating children with phonological disorders. In this article, we review changing trends in the definition of stimulability, standardized and nonstandardized approaches to its measurement, and clinical implications of stimulability for prognosis and treatment plan development as they have evolved over a 40-year period. Clinical application of stimulability information in caseload management and intervention is emphasized.