Two studies examined the impact of collaborative testing on exam scores for psychology students at a moderately selectivue Midwestern University. The first study was a replication of previous classroom research where students could choose to test with a partner or alone. No significant differences were found between those taking tests alone or with a partner. Students who scored high on extraversion and excitement seeking were more likely to choose collaborative testing. However, no significant differences were found between the students in each condition in anxiety, trust, and achievement striving. Following the classroom study, a laboratory study was conducted to tease apart the effects of studying with a partner and with testing with a partner. In Experiment 2, a strong testing effect was found, where students testing with a partner benefited, regardless of whether they studied with a partner or not. (Contains 6 tables.)