The building that serves as the headquarters of Cass District Library was constructed with federal funds received by Cass County in 1977.  Just a few months after applying for more than $800,000 in grant funds, the county broke ground for the new library building at 319 M-62 N in Cassopolis during April 1977.

In September, 1978, approximately 450 middle school students, under the supervision of school librarian Barbara Cox, moved the library from its location at the corner of Broadway and York to the new facility.  The dedication and open house were held on October 8 and the doors officially opened the following day.

On January 1, 1993, Cass County Library merged with the LaGrange Township Library, creating the Cass District Library system.  Voters approved a millage request in support of library services on September 14 of the same year.

Cass District Library's legal service area includes the Cass County townships of Calvin, Howard, Jefferson, LaGrange, Mason, Milton, Newberg, Ontwa, Penn, Pokagon, Porter, and Volinia.

Branches are located in Cassopolis, Edwardsburg, Howard, and Mason/Union and operates an affiliated computer learning center at the Cass County Council on Aging in Cassopolis.