Learner beliefs, which contribute to attitude and motivation, may affect language learning. It is therefore valuable to investigate the malleability of learner beliefs, and to determine whether potentially detrimental beliefs can be ameliorated. This study examines how instruction of the principles of Second Language Acquisition (SLA) affects students' beliefs about classroom activities and their beliefs about language learning in general. The 68 first-year German students at Brigham Young University who participated in this study were asked to rate the effectiveness of three activities typical of communicative language teaching: Dialogue activities, Peer Interview activities, and Information-gap activities. They were also asked to respond to 11 statements about language learning, seven of which were taken from the Beliefs About Language Learning Inventory(Horwitz, 1988). Students responded to the survey three times: once during the first week of the semester, again during the fourth week, and again during the eighth week. During the four weeks between the second and third surveys, students in the experimental group received seven treatment lessons based on some of the basic principles of SLA. A Repeated Measures ANCOVA and a Logistical Regression were used to determine the effects of the treatment, time, and a number of demographic variables. Results of this study show that the treatment did not have a significant effect on any of the beliefs that were measured. However, one language learning belief was significantly affected by time. A majority of the students who participated in this study agreed with the statement, “The instructor should teach the class in German.” After three weeks of class instruction, however, they agreed with this statement significantly stronger. The results of this study also show that many of the demographic variables, such as gender and previous language learning experience, had a significant effect on a number of the students' beliefs.