The Croatian Fraternal Union of America was established as the Croatian Association in 1894 in Pittsburgh, Pennsylvania, as a fraternal insurance benefit society to provide relief to Croatians in event of sickness or death. The organization changed its name in 1897 to the National Croatian Society, and adopted its present name in 1926. The Union began publishing a newspaper in 1904, issued monthly until 1909, when it began weekly publication. Membership totaled over 8,000 by 1900, over 100,000 in the 1940s, and continued to increase until the 1970s. In addition to providing members with sickness and death benefits, the Union also helped organize labor unions in the 1930s, provided relief to disaster victims worldwide, gave scholarships to students, and sponsored Croatian cultural events. "Junior nest lodges" are the youth organizations of the Union that accept members up to eighteen years old.

Six lodges of the Union are active in Montana today, and nineteen were formerly active (three as members of the Croatian League of Illinois), mainly in western Montana. Sv. Srce Isusovo Lodge 384 was organized in Roundup, Montana, in 1909, changed its name to Napredak in 1930, and was transferred into Lodge 775 in Roundup in 1952. Montana Stars Lodge 775 was organized in Roundup, Montana, in 1931, and was transferred into Lodge 84 in Anaconda, Montana, in 1981. King Tomislav Lodge 272 was organized in Lewistown, Montana, in 1904. In 1914 it was designated Lodge 4, and in 1956 Lodge 987. Junior Nest 43 was located in Roundup, Montana. The first state convention in Montana was held in Great Falls in 1914.