As technology revolutionizes instruction, conceptual models of influence are necessary to guide implementation and evaluation of specific applications such as online peer discussion. Students in an educational psychology course analyzed five case studies that applied and integrated course content. Some students (n= 42) used "WebCT Discussions" to submit their case studies; other students (n= 82) submitted written case-study analyses to their instructor. Unexpected WebCT server difficulties allowed for analysis of the impact of technology malfunction on student learning. At the beginning of the course, the groups did not differ from each other. Subsequent differences between the groups suggested benefits of online discussion until the point at which the technology malfunctioned. A model of the influence of online peer discussion is generated from the data and includes proposed mechanisms by which student learning is both positively and negatively affected by the utilization of instructional technology. (Contains 4 tables and 1 figure.)