The Federal Building, U.S. Post Office and Courthouse, Missoula, Montana, is a building housing various services of the United States federal government. Built between 1911 and 1913, an expansion initiated in 1927 and completed in 1929 allowed the building to serve thereafter as a courthouse of the United States District Court for the District of Montana. The building was again expanded in the 1930s, and was listed in the National Register of Historic Places in 1979.