Given the growing interest in retrieval practice among educators, it is valuable to know when retrieval practice does and does not improve student learning--particularly for educators who have limited classroom time and resources. In this literature review, we developed a narrow operational definition for "classroom research" compared to previous reviews of the literature. We screened nearly 2000 abstracts and systematically coded 50 experiments to establish a clearer picture of benefits from retrieval practice in real world educational settings. Our review yielded 49 effect sizes and a total n = 5374, the majority of which (57%) revealed medium or large benefits from retrieval practice. We found that retrieval practice improved learning for a variety of education levels, content areas, experimental designs, final test delays, retrieval and final test formats, and timing of retrieval practice and feedback; however, only 6% of experiments were conducted in non-WEIRD countries. Based on our review of the literature, we make eight recommendations for future research and provide educators with a better understanding of the robust benefits of retrieval practice across a range of school and classroom settings.