Theory based advising for undecided students has become even more critical with the challenges that higher education is facing due to the enrollment crisis. Advisor's need data-based tools to help isolate individual student's problems with the decision-making process. An advising "theory only focused on education or student development does not adequately address all of the stated dimensions, and therefore, advisors must reexamine the theoretical foundations from which they work" (Himes, 2014, p. 6). The purpose of this explanatory sequential mixed methods study was to examine the decision-making process of first year undecided students who were admitted to a large urban mid-western university through a First Year Academic Advising Center. This study focused on understanding the major selection process as well as the career pathway selections of the first-year undecided students participating in the program. The conceptual framework was explored through the lens of Social Cognitive Career Theory (Lent et al., 1994) using the Career Decision Self-Efficacy Scale Short Form as a tool of measurement (Betz & Taylor, 2012). The objective of this study was to develop a theory based advising protocol for undecided students. The following themes were identified as issues that impact the decision-making process for undecided students as a result of using the Career Decision Self-Efficacy Scale Short Form career determination, understanding employment trends, occupation selection, major selection, decision efficacy, plan creation, and identifying realistic majors and careers. This study was an effort to transform a current advising process to provide better service to undecided students through theory-based advising. [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.]