The Metropolitan Library System was a membership-based organization serving academic, public, school, and special libraries in Chicago and in the suburban communities of Cook, DuPage and Will counties. Established in 1966, MLS provided the leadership and resources necessary for its member libraries to succeed in their individual missions. MLS collaborated with the Illinois State Library, other library systems, and local libraries to create a seamless statewide network of information and resources for the people of Illinois. MLS merged with four organizations in 2012 to form the Reaching Across Illinois Library System.