Adult students constitute a large and increasing proportion of community college enrollment across the United States. For personal, economic, and sociological reasons, the success of these students is vital to the students themselves, the institutions they attend, and society as a whole. The purpose of this dissertation was to examine results from the Community College Survey of Student Engagement (CCSSE) to determine what variables influenced adult community college students' success as measured by cumulative GPA using Alexander Astin's I-E-O. Astin's Theory of Student Involvement was the theoretical framework for the study. Using multiple linear regression design, the study's sample included 21,386 students aged 25 and over from 589 two-year institutions. The results showed that 31 input and environmental factors were predictive of cumulative GPA. The environmental factors were primarily centered around the classroom and support services. These results may be used to inform community college practitioners and researchers to focus policies, practices, and future research on practical ways to measure, increase and support adult student success. [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.]