In computer science, students could benefit from exposure to critical programming concepts from multiple perspectives. Peer review is one method to allow students to experience authentic uses of the concepts in a non-programming manner. Peer review provides students with the opportunity to evaluate other people's work and, in doing so, allows for a rich learning experience. While much is known about peer review and it has many uses in other disciplines, the literature, especially in computer science, does not spend much time on the perspective of and benefits to the reviewer. In this work, we examine how to implement the peer review process in early, object-oriented, computer science courses as a way to develop the reviewers' higher-level thinking skills, increase their knowledge of specific programming concepts, and to improve attitudes to help engage them in the activity. Specifically, we explore peer review and its effects on Abstraction, Decomposition, and Encapsulation and how the type of review (students reviewing their peers or reviewing materials from their instructor), influences these effects. We also look at how the students' attitudes relate to their engagement in and the benefits from the reviews. To study these ideas, we used peer review exercises in two CS2 classes at local universities over the course of a semester. We divided the students into three groups where one group reviewed their peers, one group reviewed their instructor, and one group completed small design or coding exercises. We measured the students' attitudes and their conceptual understanding during the semester with surveys, tests, and concept maps. We collected the completed reviews as well. We found that reviewing helped students learn Decomposition, especially those reviewing the instructor's programs. We did not find evidence of improvements to the students' level of thinking over the semester nor were there significant changes in their attitudes. However, the data showed that students assigned to review their peers were less likely to complete the assignments than the other students were. Overall, peer reviews are a valuable method for teaching Decomposition to CS2 students and can be used as an alternative way to learn object-oriented programming concepts. / Ph. D.