The current demands of the global economy has led to an increased focus on personality and behaviors as they relate to employment outcomes for the rising number of people living with disabilities and chronic illness. There are a number of well-established and validated theories, models, and instruments that have been implemented to improve work outcomes for persons with disabilities. Additionally, in the last few decades, policy, research, and treatment enhancements have contributed to the improved job placement outcomes for persons with disabilities receiving vocational rehabilitation services. Despite these enhancements, the competitive employment rate for persons with disabilities continues to lag behind the non-disabled population. One explanation for this discrepancy may have less to do with current policy and vocational counseling interventions than previously believed. Employee behaviors and qualities identified by employers as being critical for maintaining employment and career development overlap with the behaviors and qualities that have been identified as being responsible for loss of employment for persons with disabilities. These critical work behaviors have been linked to personality development (Strauser, Waldrop & Ketz, 1999). To best conceptualize these critical work behaviors, a developmental perspective may explain how, when, and with whom they are learned. One measure that has shown promise in shedding light on these behaviors and qualities is the Developmental Work Personality Scale (DWPS), (Strauser, et al., 1999). Because of the limited use of this instrument in research, little is known about the scale's psychometric properties and its ability to discriminate among persons with disabilities who have strong employment history compared to those with less favorable employment outcomes. This study assessed the psychometric properties, determined reliability and validity measures, and established use of the DWPS to discriminate among groups. Specifically, in a sample of archival data containing 271 adults, the DWPS was found to have theoretically relevant factors, each with adequate internal consistency and adequate convergent validity with other measures of work behaviors. In a sample of 84 individuals eligible to receive vocational rehabilitation services, the factors of the DWPS were unable to classify people according to employment status. No significant differences were found between employed and unemployed participants regarding their scores on the DWPS, but significant differences and large effects were found comparing disability type, with persons with physical disabilities scoring higher on three measures of the DWPS compared to those with psychiatric disabilities. A discussion of the current economic state and limitations contributing to the scale's inability to classify according to employment status is included. Incorporation of the DWPS as a rehabilitation counseling tool may lead to improved employment outcomes particularly for persons with psychiatric disabilities. An understanding of the semiautonomous work personality for consumers of vocational rehabilitation services will likely streamline job preparedness training and improve employment outcomes for people with disabilities. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]