With the 84th Legislature's House Bill 505 expansion of dual credit in Texas in fall 2015, students became eligible to begin coursework as early as ninth grade. Allowing students to begin college earlier in their high school journey triggered questions about their college and career readiness during transition to postsecondary coursework, which has made the issue of academic and social readiness for college a continual topic due to the silo-approach towards secondary and postsecondary education college academic and social preparedness in the United States. The purpose of this study was to investigate whether participation in dual credit had any role in high school exit-level testing outcomes, and in student perceived levels of preparedness for postsecondary education. Using Schlossberg's transition theory, this mixed-methods explanatory sequential study consisted of a quantitative strand retroactive examination of dual credit enrollment levels using 2016-2019 of archival data to determine participation rates across four high school graduation cohorts, and a qualitative phenomenological interview strand based on the four self, situation, support, and strategies tenets of Schlossberg's transition theory. The key results and conclusion of the study found dual credit programs have a weakness in the social transition preparedness for students despite having positive overall reviews. Implications include inclusion into social clubs and organizations, modified instructor training, and revisions to student orientations. The main recommendation for future research is a mixed-methods study at the baccalaureate level where students come from various dual credit programs to identify any inequities between them. [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.]