This research is an exploratory multiple case study of adult serving undergraduate colleges and universities. Using the Council of Adult and Experiential Learning (CAEL) Principles of Effective Practice for Serving Adult Learners, this study examines the differences of adult serving undergraduate colleges across the three sectors of higher education--public, private not-for-profit and private for-profit. This study also seeks to determine if the presence of an adult-specific mission makes a difference in the extent to which a college may be aligned with the CAEL Principles. There were four key findings from this research. The first is that adult focused colleges in this study are aligned with 77% of CAEL Principles. The second key finding is that a new typology for classifying adult focused colleges has emerged, incorporating an adult serving ideal type, an adult learning focused ideal type, and an adult focused mixed type. A third key finding from the study is that the presence of an adult-specific mission appears to have more of an impact on the alignment of adult focused colleges to the CAEL Principles than sector. And, finally, the fourth key finding from this study is that the lack of definitive evidence to support how sector plays a role in determining the extent to which an adult focused college may be aligned with CAEL Principles disputes the assertion by some voices in the field that private for-profit colleges are uniquely suited to serve adult students merely because of their for-profit status. According to the data represented in this study, it appears that if there is any trend by sector, it is that public and private not-for-profit colleges are at least as well suited, if not more so, to serve adult students. Organizational culture theory and the literatures on adult learners, adult learning theory, ideal types and private for-profit colleges provide the theoretical foundations for this research. [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.]