| Abbreviation | Definition |
|---|---|
| MLLH | Melton Library and Learning Hub |
| MLLL | Medicine Lodge Lincoln Library (Medicine Lodge, KS) |
| MLN | Mountain Library Network |
| MLNC | Missouri Library Network Corporation |
| MLS | Massachusetts Library System |
| MLS | Master's of Library Science |
| MLS | Metropolitan Library System |
| MLSA | Museum and Library Services Act |
| MMCL | Mining Mineral and Cement Library |
| MMDL | Management Measures Digital Library |
| MMDL | Myanmar Manuscript Digital Library |
| MML | Mizar Mathematical Library |
| MMML | Monastic Manuscript Microfilm Library |
| MMWR | Morbidity and Mortality Weekly Report |
| MOBIUS | Missouri Bibliographic Information User System |
| MOGL | Marshes Of Glynn Libraries |
| MOLO | Mideastern Ohio Library Organization |
| MPL | Madison Public Library |
| MPL | Markham Public Library |
| MPL | Medford Public Library |