The purpose of this study was to develop a reliable and valid Likert scaled instrument to predict adult non-high school degree holders who would perform well academically in a project-based learning (PBL) assessment environment to obtain their high school diploma as opposed to traditional standardized tests such as the General Educational Development (GED), Test Assessing Secondary Completion (TASC), and High School Equivalency Test (HiSET). For the purposes of the initial investigation, two dimensions were assumed based on this literature review: (1) Authenticity in learning and genuine curiosity; (2) Collaboration. This instrument was found to be a reliable instrument based on the Cronbach's alpha of the subscales for nine of ten of the subscales. The instrument was found to be a valid instrument based on a literature review of project-based learning and an assessment of the questions by a panel which included experts in project-based learning and experts in adult high school completion programs. [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.]