The testing effect is a robust empirical finding in the research on learning and instruction, demonstrating that taking tests during the learning phase facilitates later retrieval from long-term memory. Early evidence came mainly from laboratory studies, though in recent years applied educational researchers have become increasingly interested in the effects of retrieval practice. We investigated the extent that the testing effect can also be observed and effectively used in psychology classes. Inspection of the research literature yielded 19 publications that tested the effect in the context of learning and teaching psychology. A total of 72 effect sizes were extracted from these publications and subjected to a meta-analysis. A significant overall effect size of d = 0.56 demonstrated that testing was beneficial to the learning outcomes. Further analyses focussed on the role of potential moderator variables, a possible publication bias, and the dependency between effect sizes. The results are discussed in the context of applications in learning and teaching psychology.