The departure of an effective school leader can influence staff turnover and student achievement for several years. With school systems facing an unprecedented public health crisis due to COVID-19, principal retention is a key area of concern for many local and state education agencies. The Regional Educational Laboratory West undertook this study of principal retention rates to help leaders in Arizona, Nevada, and Utah better understand principal retention patterns in their state, so that their new statewide leadership support initiatives could identify areas where support could be most effective. Findings showed that fewer than half of principals in each of these states remained at the same school from fall 2016 to fall 2020 (four year retention). The study also found that principals who changed jobs (but remained in the principalship) tended to move to a new school in the same local education agency rather than to a new school in another local education agency. Principal retention patterns varied by state according to grade span, school locale type, and student demographic characteristics. In addition, across the three states, proportionally fewer principals remained at schools with lower average proficiency rates on standardized tests in math and English language arts than at schools with higher average proficiency rates from fall 2016 to fall 2019 (three year retention). [For the Study Snapshot, see ED617165. For the appendixes, see ED617166.]