Membership is available to any Metrowest region library that meets the basic requirements set forth by the Massachusetts Board of Library Commissioners. There is no fee for membership.
| Institution | Library | City | Date Joined | Type of Library |
| Ashland Middle School | School Library | Ashland | 11/26/07 | School |
| North Cambridge Catholic High School | School Library | Cambridge | 1/23/08 | School |
| Dedham Historical Society | Library | Dedham | 11/15/07 | Special |
| Center Elementary School | School Library | Stow | 9/27/2007 | School |
| Pompositticut Elementary School | School Library | Stow | 9/27/2007 | School |
| Ambrose Elementary School | School Library | Winchester | 2/14/08 | School |
| Lincoln Elementary School | School Library | Winchester | 2/14/08 | School |
| Lynch Elementary School | School Library | Winchester | 2/14/08 | School |
| Muraco Elementary School | School Library | Winchester | 2/14/08 | School |
| Vinson Owen Elementary School | School Library | Winchester | 2/14/08 | School |
Metrowest strives to be responsive to the needs of its members. Services provided include access to a number of on-line databases, supplemental reference assistance, interlibrary loan, staff development and continuing education, a material and supply cooperative, and delivery of books and other library materials. For more details see Services for Metrowest Regional Library System Members.
Additional services for member libraries of the Regional Library System are provided by the Boston Public Library. Those services include Supplemental Reference assistance for requests that are beyond the available resources of the regional reference center at the Newton Free Public Library. In addition the Boston Public Library will assist in citation verification, interlibrary loan support, journal document delivery, and film and video advanced bookings.
Librarians are encouraged to participate in the region's discussion list. Subscribe at http://www.mmrls.org/about.htm. Select Subscribe to Metrowest Electronic Discussion List.
In addition, you may keep up to date with the developments of the Metrowest Massachusetts Regional Library System through the internet at www.mmrls.org.
Any public, academic, school, and special library within the Metrowest region will be eligible to participate as a member of the Metrowest Massachusetts Regional Library System upon meeting the following requirements: