The purpose of this research was to explore the lived experiences of high school mathematics teachers with regards to postsecondary readiness, specifically how those experiences informed their perceptions of and experience with developing postsecondary readiness skills in their students. Semi-structured interviews were conducted in person and via Zoom with high school mathematics teachers at a public charter school in Central Oregon. Social cognitive theory was used as a theoretical framework that explored aspects of human agency in an educational environment. Four themes emerged from the analysis of the interview data: 1) high schools generally prepare students for postsecondary life, but do not always provide a comprehensive preparation in all areas, 2) the most memorably transferable academic skills are related to college majors or areas of study, and teachers play a critical role in developing those skills, 3) crucial nonacademic readiness skills are learned in a variety of environments, with inconsistent attention paid to this skill development in academic settings, and 4) teachers understand the importance of developing students' nonacademic readiness skills, but are largely underprepared in best practices to teach and measure these skills. These findings provide insight into the various factors that influence mathematics teachers in their approach to developing student postsecondary readiness skills in both the academic and nonacademic realms and contribute to the discussion of how best to prepare students for all postsecondary endeavors. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]