Rosalia is a town in Whitman County, Washington, United States. It is an agricultural community in the Palouse region, at an elevation of 2,238 feet (682 m) above sea level. Its population was 598 at the 2020 census.

Whitman County is a county located in the U.S. state of Washington. As of the 2020 census, the population was 47,973. The county seat is Colfax, and its largest city is Pullman.