The purpose of this study was to determine the effectiveness of the implementation of case-based learning compared to traditional lecture in increasing critical thinking skills in an undergraduate Anatomy & Physiology I classroom. Throughout the course of one semester, five units were taught with the addition of a case study as an instructional tool while the other four units were taught utilizing only didactic (lecture) methods and did not teach content utilizing case study methodology. Two types of content-specific critical thinking data were analyzed: selected multiple-choice exam questions and End of Chapter (EOC) assignments. The Cornell Critical Thinking Test (CCTT) was administered at the beginning and end of the semester to measure general critical thinking skill progress throughout the course. In addition, the Student Assessment of Learning Gains (SALG) survey was administered at the end of the semester to measure student perception of learning via different teaching methodologies. Exam data indicated a growth in content-specific critical thinking throughout the semester while EOC data were inconclusive. The CCTT data showed an overall lack of change in critical thinking skills. Students perceive case studies as generally helpful for learning, but rate lecture and laboratories as providing more assistance in learning course material. [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.]