This paper describes an online system that facilitates peer assessment of students' course work and then uses data from individual case writing assignments in introductory financial accounting to empirically examine associations between peer assessment and case writing performance. Through this description and empirical analysis, the paper addresses the following questions: (1) Why use peer assessment? (2) How does online peer assessment work? (3) Is student peer assessment reliable? (4) What do students think of peer assessment? (5) Does student peer assessment contribute to academic performance? Three key findings from this study are that students at the sophomore level were able to generate reasonably reliable feedback for peers, they valued the experiences involved in providing peer feedback, and giving quality feedback had a more significant and enduring impact on students' accounting case analyses than did receiving quality feedback, after controlling for differences in accounting knowledge and case writing skills.