图书借阅证，英文称为Library Card，一般又有借书证，或阅览证的称呼，形式从一般的纸卡到磁卡都有。它对于读者而言不是必须的，但若拥有它，读者才能使用图书馆的全部服务，如借书、使用视听数据等，在部分设有门禁系统的图书馆里，读者更是必须拥有这项证件才能进入图书馆内。

一般来说，读者若想办理图书借阅证，需在达到图书馆规定的年龄后，持身份证明文档前去图书馆柜台申请方可取得(但若读者是学生身份，且只想使用学校图书馆的服务时，其学生证通常就是图书借阅证，不用再另行办理)。

图书借阅证的功能随着图书馆的规定而有不同，如在台湾的国家图书馆中，就只能用来调阅数据，而不能借出，因此称为阅览证而不称为借阅证。但在一般图书馆中，除了图书馆所限制的数据外(如期刊、参考书、珍贵的善本书)，都可借出。此外，倘若读者所在的图书馆与别的图书馆有合作关系，这个证件也可以用来使用馆际互借等服务。

A library card can refer to several cards traditionally used for the management of books and patrons in a library. In its most common use, a library card serves similar functions as a membership card. A person who holds a library card has borrowing or other privileges associated with the issuing library. The library card also serves as a method of identification. When a person chooses an item to borrow and presents his or her library card to the library, he or she takes responsibility for the borrowed item and promises to abide by certain rules, usually including a promise to return the item by the due date or face a library fine. If the cardholder violates these responsibilities, his or her borrowing privileges may be suspended. As of 2011, 62% of all Americans are library cardholders.