Messengers for Health serves the communities of the Crow Reservation. Established in1868, the Crow Indian Reservation is located in south-central Montana, bordered by Wyoming to the south and the Northern Cheyenne Indian Reservation to the east. The largest of the seven Indian reservations in Montana, it encompasses approximately 2,300,000 acres (9,300 km2), which includes the northern end of the Bighorn Mountains, Wolf Mountains, and Pryor Mountains. The Bighorn River flows north from the Montana-Wyoming state line, journeying north to the Little Bighorn River just outside Hardin, Montana. Part of the reservation boundary runs along the ridgeline separating Pryor Creek and the Yellowstone River. Reservation headquarters are in Crow Agency.

The Crow Tribe of Indians of the State of Montana has an enrolled tribal membership of approximately 11,000, of whom 7,900 reside on the Crow Indian Reservation. Eighty-five percent speak Crow as their first language. The Crow communities include: Crow Agency, Fort Smith,Hardin, Lodge Grass, Pryor, St. Xavier, and Wyola.