Sharing digital libraries

In some implementations, a first user associated with a first user account may send a request to exchange digital libraries with a second user associated with a second user account. Upon acceptance, the second user receives first library information associated with the first user account that identifies content items that may be accessed by the second user due to the exchange. Similarly, the first user receives second library information associated with the second user account that identifies second content items that may be accessed by the first user. In other examples, a user may access the digital library of a selected person or entity, such as a historical figure, celebrity, author, friend, or organization. Additionally, in some cases, a user may view content of a content item that a selected person is currently reading, and which may include annotations made to the content item by the selected person.