The purpose of this study was to assess the effect of a 3-stage community college mathematics teacher and curriculum conceptual change program on student achievement. The study, which was a replication and extension of Lake (2008), was conducted during Fall 2009 and Spring 2010 terms and focused on teachers' instructional practices relative to three learning principles: engaging students' preconceptions, developing conceptual frameworks, and promoting students' metacognition. The targeted course was liberal arts mathematics, and the topics were sets, logic, probability, counting, statistics, and geometry. Stage 1 was a 5-week, 30-hour conceptual change inservice on contemporary learning theory and how students learn mathematics. Stage 2 consisted of practical action research in which two Stage 1 participants implemented theory-based instructional strategies and reflected on their experiences. Stage 3 was a retrospective study that assessed the overall impact of Stages 1 and 2 by comparing comprehensive final examination scores between students whose teachers did (treatment, n = 60) or did not (control, n = 52) participate in Stages 1 and 2. All treatment students completed a survey at the end of each unit examination to self-assess their metacognitive and self-regulation strategies. Students in one treatment group also used a textbook that was aligned to the three learning principles. The study's findings revealed that the teachers did not integrate the theory-based resources from the textbook into their lessons. They also did not promote students' metacognition by reviewing students' responses to the survey, relating the responses to students' unit examination grades, and discussing these results with the students. Instead, the teachers placed the onus on students to become cognizant of their own metacognition by having them complete the survey at the end of each examination and awarding them extra credit for doing so. The findings also indicated that the primary barriers to aligning instructional practices to the three learning principles were insufficient time and lack of student responsibility. Statistical results of final examination scores showed no significant treatment effect, but the combination of treatment and years teaching mathematics was significant. [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.]