The Substance Abuse Subtle Screening Inventory-3 (SASSI-3; Miller & Lazowski, 1999) is a popular screening instrument used to assist professionals in the assessment of individuals who may be substance dependent. Many researchers have reported reliability and validity results on this instrument with mixed results, which at times have contradicted those published by the authors of the instrument. This study is the first to explore the fundamental measurement properties of the SASSI-3 from a Thurstonian perspective. Included in this dissertation are a comprehensive review of the literature on the SASSI-3's psychometric properties and a discussion of the methods used to evaluate the instrument. The results demonstrated that the whole SASSI-3 meets fundamental measurement properties and can discriminate groups of people from high to low on the substance dependency variable. However, the face valid scales continue to demonstrate higher functioning when used independently of the subtle items. Based on these results, future research recommendations include combining the Face Valid Alcohol and Face Valid Other Drug scales to determine the functioning of these two scales together. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]