Texas education is experiencing dramatic increases in enrollment in early college high school (ECHS) programs, and new programs are being developed equally quickly across the state. These programs require a partnership between secondary and postsecondary institutions, and system boundaries can be tricky for leaders to navigate when differences in policy, operation, or philosophy arise. Leaders involved in scaling ECHS programs must engage a specific skill set to navigate those boundaries. The purpose of this phenomenological study was to explore the boundaries that high school and college administrators, called "boundary spanners" in this context, experienced in concurrent enrollment partnerships and how they navigated those boundaries when scaling a new ECHS together. In the findings of this study, drawn from focus group and interview data, boundary spanners identified themes in the challenges they encountered within the four dimensions of social capital--structural, relational, cognitive, and action-oriented--and they relied heavily on global leadership competencies, including cultural self-awareness, inviting the unknown, cultivation of relationships, frame-shifting, adapting and adding value, influencing across boundaries, and third-way solutions to navigate them. This study addresses a critical gap in the literature, and it looks at only one ECHS partnership in Central Texas, so many more studies like it are warranted in the future. [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.]