On May 21, 2021, this report was posted as an MMWR Early Release on the MMWR website (https://www.cdc.gov/mmwr).Cessation of kindergarten through grade 12 in-person instruction and extracurricular activities, which has often occurred during the COVID-19 pandemic, can have negative social, emotional, and educational consequences for children (1,2). Although preventive measures such as masking, physical distancing, hand hygiene, and improved ventilation are commonly used in schools to reduce transmission of SARS-CoV-2, the virus that causes COVID-19, and support in-person instruction (3-6), routine school-based COVID-19 testing has not been as widely implemented. In addition to these types of standard preventive measures, Utah health and school partners implemented two high school testing programs to sustain extracurricular activities and in-person instruction and help identify SARS-CoV-2 infections: 1) Test to Play,* in which testing every 14 days was mandated for participation in extracurricular activities; and 2) Test to Stay, † which involved school-wide testing to continue in-person instruction as an alternative to transitioning to remote instruction if a school crossed a defined outbreak threshold (3). During November 30, 2020-March 20, 2021, among 59,552 students tested through these programs, 1,886 (3.2%) received a positive result. Test to Play was implemented at 127 (66%) of Utah's 193 public high schools and facilitated completion of approximately 95% of scheduled high school extracurricular winter athletics * Test to Play, which required testing every 14 days for participants in high school extracurricular activities, is described in the Utah COVID-19 School Manual (https://coronavirus-download.utah.gov/School/COVID-19_School_Manual_ FINAL.pdf ) and was mandated by Utah State Public Health Order 2020-25 (https://coronavirus-download.utah.gov/Health/UPHO_2020-25_Statewide_ COVID-19_Restrictions.pdf ), effective November 30, 2020. † Beginning August 2020, schools were advised to transition to remote instruction for 14 days when the number of school-associated cases among students and staff members crossed a specified outbreak threshold. During August-December 2020, the outbreak threshold was 15 school-associated cases during the previous 14 days. Under Test to Stay (https://coronavirus-download.utah.gov/School/ COVID-19_School_Manual_FINAL.pdf ), which began January 4, 2021, the outbreak threshold of cases during the previous 14 days changed to 1% of the school population for schools with >1,500 students and staff members and 15 cases for schools with ≤1,500 students and staff members, and the period of advised remote instruction after crossing the outbreak threshold changed to 10 days. Beginning March 24, 2021 (after the study period), per Utah Senate Bill 107 (https://le.utah.gov/~2021/bills/static/SB0107.html), the outbreak threshold changed again, such that a school would be required to conduct Test to Stay if student cases during the previous 14 days reached 2% of the school's student population for ...