ACT retesting occurs when students take the ACT® test multiple times with the goal of improving their scores and postsecondary credentials. In this paper, the author examines preliminary data for the 2022 ACT-tested graduating cohort to better understand the ACT score gains that occur with retesting. The author presents the following six things to know about ACT score gains from retesting: (1) Average score gains are modest (about 1 score point); (2) Score gains increase with more time between tests; (3) Higher-achieving students tend to have larger score gains; (4) Differences in score gains across demographic groups are small but consistent with long-standing achievement gaps; (5) ACT scores tend to increase with additional retesting, but there are diminishing returns; and (6) ACT Superscore gains are substantially larger than ACT Composite score gains.