Correctional and detention facilities face unique challenges in the control of infectious diseases, including coronavirus disease 2019 (COVID-19) (1-3). Among >10 million annual admissions to U.S. jails, approximately 55% of detainees are released back into their communities each week (4); in addition, staff members at correctional and detention facilities are members of their local communities. Thus, high rates of COVID-19 in correctional and detention facilities also have the potential to influence broader community transmission. In March 2020, the Louisiana Department of Health (LDH) began implementing surveillance for COVID-19 among correctional and detention facilities in Louisiana and identified cases and outbreaks in many facilities. In response, LDH and CDC developed and deployed the COVID-19 Management Assessment and Response (CMAR) tool to guide technical assistance focused on infection prevention and control policies and case management with correctional and detention facilities. This report describes COVID-19 prevalence in correctional and detention facilities detected through surveillance and findings of the CMAR assessment. During March 25-April 22, 489 laboratory-confirmed COVID-19 cases, including 37 (7.6%) hospitalizations and 10 (2.0%) deaths among incarcerated or detained persons, and 253 cases, including 19 (7.5%) hospitalizations and four (1.6%) deaths among staff members were reported. During April 8-22, CMAR telephone-based assessments were conducted with 13 of 31 (42%) facilities with laboratory-confirmed cases and 11 of 113 (10%) facilities without known cases. Administrators had awareness and overall understanding of CDC guidance for prevention of transmission in these facilities but reported challenges in implementation, related to limited space to quarantine close contacts of COVID-19 patients and inability of incarcerated and detained persons to engage in social distancing, particularly in dormitory-style housing. CMAR was a useful tool that helped state and federal public health officials assist multiple correctional and detention facilities to better manage COVID-19 patients and guide control activities to prevent or mitigate transmission.