Instructors across disciplines continue to seek methods to improve students' retention of class material. One potential method for increasing retention is the use of collaborative, or group, testing. We tested the hypothesis that group testing would lead to greater retention than individual testing. Two instructors, teaching 2 sections of their respective courses, alternated testing formats across the 2 courses. Participants were 147 students from 4 separate undergraduate psychology courses (2 per instructor). Participants taking the group test initially scored higher than those taking the individual test. However, after 3 weeks, with retesting on a subset of questions, there was no significant difference in retention between group versus individual test takers. These findings call into question the value of collaborative testing. (Contains 2 tables, 2 notes and 1 footnote.)