BACKGROUND: Test‐to‐stay (TTS) is a strategy to limit school exclusion following an exposure to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). We evaluated the use of TTS within universally masked kindergarten through 12th grade (K‐12) school settings following household SARS‐CoV‐2 exposure. METHODS: Three hundred twenty‐two participants were enrolled. Serial rapid antigen testing was performed up to 15 days post‐exposure. Analysis‐eligible participants completed the 15‐day testing protocol, tested positive any time during the testing window, or received a negative test on or after day 9. Primary outcomes included within‐school tertiary attack rate (TAR) (test positivity among close contacts of positive TTS participants), and school days saved among TTS participants. RESULTS: Seventy‐three of 265 analysis‐eligible participants tested positive for SARS‐CoV‐2 (secondary attack rate of 28% [95% CI: 16‐63%]). Among 77 within‐school close contacts, 2 were positive (TAR = 3% [95% CI: 1‐5%]). Participant absences were limited to 338 days, resulting in 82% of 1849 school days saved. IMPLICATIONS FOR SCHOOL HEALTH POLICY, PRACTICE, AND EQUITY: TTS facilitates continued in‐person learning and can greatly reduce the number of missed school days. CONCLUSIONS: Within universally masked K‐12 schools, TTS is a safe alternative to school exclusion following household SARS‐CoV‐2 exposure. [ABSTRACT FROM AUTHOR]