The purpose of this study was to determine if a case-based reasoning tool would improve a student's understanding of the complex concepts in a Java programming course. Subjects for the study were randomly assigned from two sections of an introductory Java programming course. Posttests were used to measure the effects of the case-based reasoning tool (CBJava) on learner competency. Results of the study using a Mann-Whitney U test indicated a significant difference between the group who used CBJava on complex questions and the group who did not "(m rank = 11.50; U = 3.500, p less than 0.05, M = 22.71 vs. M = 17.88)". No significant difference was indicated between the groups on simple questions. Recommendations from this study include supporting complex content through examples, providing a case-based instructional aid for complex topics, and extending CBJava's framework to support other courses and disciplines. (Contains 5 tables and 1 figure.)