France has an excellent public library system, with many branches scattered throughout major cities and small towns. You can find local libraries through the LibWeb site. If you do not see a library listed in your town, click on a link for a nearby library. Larger libraries on this page often provide links to smaller local libraries.
French public libraries will probably feel familiar to you. They offer many of the same services as their American counterparts, including fiction and nonfiction, local information, Internet access, and online databases. Make sure to check on membership requirements before applying for a public library card. You may be asked to bring various documents and a photograph. Some public libraries require a small fee. If your local library costs money, ask if you can pay for membership for the length of time you will be in France. Some French public library systems will allow you to pay by the month, week, or individual visit.
Smaller public libraries tend to cater towards the schedules of working adults. They are often open on afternoons and evenings on weekdays, and mornings and afternoons on Saturdays.
Bibliothèque publique d'information
Housed in Paris's Pompidou Center, the Bibliothèque publique d'information (BPI) has a huge collection, open stacks, and convenient hours. It also provides museum-style exhibitions, cinema festivals, and other cultural events. Returning students rate this as one of the most useful libraries in Paris for conducting research.
American Library in Paris
The American Library in Paris has served English-speaking Parisians and visitors for over 80 years. It is open Tuesdays through Saturdays, 10 AM to 7 PM. Visit the library to borrow popular and educational materials in English, and see special events such as book signings. Membership is required; click the membership link on the web page for details.

Bibliothèque Nationale de France
France's national library, the Bibliothèque Nationale de France (BnF), offers many services to the public. Most of its historical print resources are in closed stacks. However you can request copies of historical materials from its impressive collection. Many of its electronic resources are available to the general public, or to members, though the Bibliotheque's web site. Be sure to read through the admissions information before coming to the BnF. Admission passes are available for various combinations of time periods and resources. Depending on which resources you would like to use, you may have to go through an interview with a librarian before you are permitted access. You can use BnF's Ask a Librarian service, in English or French, if you have questions.