| LA | : | Library Association |
| LA (UK) | : | The Library Association of the United Kingdom |
| LAA | : | Library Association of Australia |
| LAB | : | Library Association of Bangladesh |
| LAC | : | Library Association of China |
| LAN | : | Local Area Network |
| LAP-B | : | Link Access Procedure – Balanced Protocol |
| LAPL | : | Library Association Publishing Limited |
| LASER | : | London and Southeast Regional Library Bureau |
| LAUK | : | Library Association of the United Kingdom; now the Library Association |
| LC | : | Library of Congress |
| LCC | : | Library of Congress Classification |
| LCCDG | : | Library Collections Conservation Discussion Group |
| LCMARC | : | Library of Congress Machine-Readable Cataloging |
| LCSH | : | Library of Congress Subject Headings |
| LED | : | Light-Emitting Diode |
| LIBRIS | : | Library and Information System |
| LINC | : | Library and Information Co-operation Council |
| LIP | : | Library and Information Plan |
| LIS | : | Library and Information Science |
| LISA | : | Library and Information Science Abstract |
| LISC | : | Library and Information Science |
| LIST | : | Library and Information Science Today |
| LITA | : | Library and Information technology Association |
| LIU | : | Local Information Unit |
| LLA | : | Local Information Unit |
| LLC | : | Logical Link Control |
| LML | : | Logical Link Control |
| LOCAS | : | Local catalogue Service |
| LOCIS | : | Library of Congress Information System |
| LOEX | : | Library Orientation Instruction Exchange |
| LP | : | Long-Playing Record |
| LSA | : | Library science Abstract |
| LSI | : | Large Scale Integration |
| LUCI | : | Logical Unit based Cyclic Index |