In 1936, members of St. Mary's Church of Sleepy Eye, Minnesota, seeking a place to save and borrow money at reasonable interest rates, organized to form a credit union. The original bylaws of the credit union were signed by A. J. Bertrand, A.J. Pietrus, Mark A. Wooldrik, F. Jerome Riedl, P.J. Guldan, John Ebenhoh, Henry Leitschuh and C. P. Cutting on April 21, 1936 under the charter name of St. Mary's Parish Sleepy Eye Credit Union.
The credit union's original field of membership was limited to members of St. Mary's Parish of Sleepy Eye, their immediate families and associations of such members. In 1938, the field of membership was expanded to add the members of the Japanese Martyrs Church of Leavenworth. Another expansion happened in 1965, when membership was extended to all members of the parishes of the New Ulm Diocese that resided in Brown County. The final change to the field of membership occurred on February 21, 2002 when all residents and legal entities of Brown, Redwood and Renville counties of Minnesota were added.