Although testing has repeatedly been shown to be one of the most effective strategies for consolidating retention of studied information (the backward testing effect) and facilitating mastery of new information (the forward testing effect), few studies have explored individual differences in the beneficial effects of testing. The current study recruited a large sample (1,032 participants) to explore the potential roles of working memory capacity and test anxiety in the enhancing effects of testing on new learning, and the converse influence of testing on test anxiety. The results demonstrated that administering interim tests during learning appears to be an effective technique to potentiate new learning, regardless of working memory capacity and test anxiety. At a final test on all studied materials, individuals with low working memory capacity benefited more from interim testing than those with high working memory capacity. These testing effects are minimally modulated by levels of trait/state test anxiety, and low-stake interim testing neither reduced nor increased test anxiety. Overall, the results imply that low-stake interim tests can be administered to boost new learning irrespective of learners' level of WMC, test anxiety, and of possible reactive effects of testing on test anxiety. (PsycInfo Database Record (c) 2020 APA, all rights reserved).