Four investigations were completed to develop a self-report measure of ego-identity status. Following James Marcia's definition of diffusion, moratorium,

foreclosure, and identity achievement status, a series of Likert-type items were constructed and validated for use in the study of ego-identity formation. Convergent-divergent, concurrent, and predictive validity and test-retest reliability are documented in the reported data. Cross-sectional data suggest the measure will be sensitive to intraindividual change in identity formation. The new Objective Measure of Ego-Identity Status allows researchers to use either a "typology" or a "distribution of stage responses" in future longitudinal investigations.