This paper analyzes the importance of corpus use on L2 vocabulary learning and of moderators on effectiveness. It is constructed around 29 studies identifying 38 unique samples, which met numerous criteria for inclusion (e.g. with control groups), and showed a total positive medium-sized effect of corpus use on L2 vocabulary learning for both short-term (77 posttest effect sizes; Hedges’ g = 0.74, SE = 0.09, p < .001) and long-term intervals (34 follow-up effect sizes; Hedges’ g = 0.64, SE = 0.17, p < .001). It also highlighted considerable variation in adjusted mean effect sizes across moderators. In particular, in-depth vocabulary knowledge showed a prominent effect, while learners’ L2 proficiency and some characteristics of corpus use more greatly affect the effectiveness of corpus use in improving L2 vocabulary learning.