The Harvard Library is the umbrella organization for the Harvard University libraries and their shared services, such as access, preservation, digital infrastructure, digital imaging, and discovery services. The Harvard Library is nearly 400 years old, making it the oldest library system in the United States. Additionally, the Harvard Library is the largest private library system and largest academic library in the world. Its collection holds nearly 20 million volumes, 400 million manuscripts, 10 million photographs, and one million maps.

Harvard Library holds the third largest collection in the United States, after the Library of Congress and Boston Public Library. Based on the number of items held, it is the fifth largest library in the United States. Additionally, Harvard is part of the Research Collections and Preservation Consortium (ReCAP) along with Columbia Libraries, Princeton University Library and New York Public Library, and the Ivy Plus Libraries Confederation, making over 90 million books available to the library's users.