Adult students are now enrolling into colleges and universities in large numbers. Their life responsibilities and time away from school create challenges for academic success. A portion of these learners are also non-native English speakers who face compounded difficulties. One of the skill areas that these students need to cultivate is academic writing. In order for students to be successful in college coursework, they need to be able to express their ideas and knowledge development in written form. This study examined how well these students acquire those skills. Four research questions were posed: 1) to what degree do native-speaking adult learners acquire academic writing skills, 2) to what degree do non-native speaking adult learners acquire academic writing skills, 3) to what degree do adult learners acquire critical thinking skills in a first-year composition course, and 4) how does perceived student writing ability correlate to actual writing performance. A multi-case, mixed methods methodology was utilized to address the research questions. [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/en-US/products/dissertations/individuals.shtml.]