Legal deposit is a legal requirement that a person or group submit copies of their publications to a repository, usually a library. The number of copies required varies from country to country. Typically, the national library is the primary repository of these copies. In some countries there is also a legal deposit requirement placed on the government, and it is required to send copies of documents to publicly accessible libraries.

The Bibliothèque et Archives nationales du Québec or BAnQ is a Quebec government agency which manages the province's legal deposit system, national archives, and national library. Located at the Grande Bibliothèque in Montreal, the BAnQ was created by the merging of the Bibliothèque nationale du Québec and the Archives nationales du Québec in 2006. The Bibliothèque nationale du Québec had previously merged with the Grande Bibliothèque du Québec in 2002.