CDC has released targeted tools to help protect congregate and health care environments from measles. These tools are especially valuable for settings in which transmission risk is higher, or control may be more challenging. The correctional facility checklist guides correctional staff working alongside local health departments on how to prepare and what steps to take in the first critical 10 minutes after a suspected measles case. A companion checklist for congregate shelters offers tailored guidance for isolation procedures, symptom awareness, vaccination requirements, and referral protocols.