Inequities in STEM persist, notably in underrepresented groups relating to gender, race, socio-economic status, and disability. The purpose of this study was to explore correlations between STEM identities, personal identities, mentor-related experiences, and academic/career persistence of undergraduate students in Idaho public post-secondary institutions. This study was guided by Gee's (2001) identity theory, Carlone and Johnson's (2007) STEM-ID model, and Martin's (2007) motivation and engagement wheel. These theories emphasized the critical roles that identity, experience, and perception play in student success. A pilot study was conducted at the University of Idaho in Spring 2024. Based on the results, modifications were made to the survey instrument to ensure validity and reliability in the STEM identity assessment, as well as adequately address the research questions. Additionally, data from the pilot study was used to create an outline for the Grit-Oriented Student Success (GOSS) model. The survey was readministered in Fall 2024 on a statewide level. Participants from College of Eastern Idaho, College of Southern Idaho, North Idaho College, and the University of Idaho (n = 579) completed the survey in the first half of the fall semester. Quantitative data analysis indicated that, overall, undergraduate students at Idaho post-secondary institutions had slightly positive STEM identities, with areas ranked high to low "performance and competence" (M = 3.95, SD = 0.79), "belonging" (M = 3.74, SD = 0.95), "recognition" (M = 3.67, SD = 0.91), and "interest" (M = 3.65, SD = 1.07). Data also indicated that there were significant differences in STEM identities for all academic and personal demographics explored. Qualitative data was used to determine three types of mentors: mentor, role model, and support person. Significant differences were indicated in participants' STEM identities in positive mentor experiences, positive role model experiences, support person, negative mentor experiences, and negative role model experiences. Results suggest additional research should be conducted to further explore the impact of these mentor types on STEM identities. STEM-related career persistence was explored in three areas. Participants who were pursuing the same career they were interested in as a child ranked themselves higher in two "interest" statements, indicating that long-term interest in goals could indicate higher levels of confidence and persistence in academic/career and future life goals. There were significant differences in all STEM identities statements between participants who are pursuing and not pursuing a STEM-related career--with those pursuing a STEM-related career ranking themselves higher on every statement. Additionally, participants who anticipated STEM-related barriers ranked themselves lower on eight "recognition" statements, four of the six "performance and competence" statements, one "interest" statement, and two "belonging" statements, indicating a correlation between lower STEM identities and perceived barriers. Further research should be conducted to explore these correlations in more detail. Seven themes emerged in the qualitative analysis: (1) Importance of Positive Career-Related Performance/Competence Experience, (2) The Epiphany Experience!, (3) Importance of a Mentor-Related Figure, (4) Passion vs Practicality, (5) (Mis)understanding STEM, (6) Barriers to STEM, and (7) Flip a Negative. These themes were used to develop the Grit-Oriented Student Success (GOSS) model. The GOSS model diagramed an "equation" for student success, through the lens of academic/career persistence, focusing on three main components: motivation, engagement, and barriers (overcome). All data from this research can be used as a baseline to inform future research on personal/academic identity, STEM identity, mentor-related experiences, and academic/career persistence for undergraduate students in the state of Idaho. [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.]