Knowledge and information are the foundations for economic activity, thus current legislation is designed to strengthen and improve the nation's public workforce system. Despite the heightened visibility of adult mathematics in surveys of adult skills like PIAAC and the implementation of College and Career Readiness Standards for Adult Education, our institutions are failing to meet the needs of adult learners. Recent efforts call for classroom environments where students have opportunities to reason and construct viable arguments. To this end, a descriptive single case study of a collaborative adult education mathematics classroom was undertaken. This study contributes to our understanding of adult learning in the mathematics classroom. It provides a perspective on how knowledge is constructed through interaction and the opportunities available to students to explain and engage with others' ideas. This study provides an example of how one classroom, centering adults' mathematical thinking, developed over time. [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.]