The development of employee expertise is described as a strategic imperative for ever-changing organizations in a hyper-competitive economic environment. However, the lack of an adequate assessment tool for expertise has hindered empirical research. This paper conceptually and empirically develops the generalized expertise measure (GEM) and examines its psychometric properties in two managerial samples. Schwab's (1980) three stages of measure development process are followed. The factor structure of the measure is then examined employing exploratory factor analysis (EFA) procedures and confirmed using confirmatory factor analysis (CFA) on independent samples. The results are presented and a preliminary measure of expertise is provided.