This two-part study used Ecological Systems Theory to explore college readiness of dual enrollment students across online, high school, and college campus settings. First, a causal-comparative study was used to examine if and to what extent dual enrollment students' perceptions of college readiness differed depending on course location, and a follow-up phenomenological study explored experiences of college readiness after matriculating to a college or university. The research questions sought to discover whether students' perceptions of college readiness differed by course location and how former dual enrollment students described experiences of college readiness in retrospect. Samples included 164 students who took dual enrollment courses at a four-year institution in the rural southwest between 2013 and 2016 and used preexisting data from the Dual Enrollment Survey and a series of semi-structured interviews. In the causal-comparative portion, scales for academic readiness, non-academic readiness, and overall college readiness were analyzed using the Kruskal-Wallis test. Results showed that there were no differences in dual enrollment students' perceptions of academic readiness (p = .643), non-academic readiness (p = 0.136), or overall college readiness (p = 0.252) depending on dual enrollment course location. In the second part of the study, interviews were transcribed, coded, narrowed to themes, and compared to describe experiences of college readiness across settings. [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.]