The Biblioteca Comunale degli Intronati is the public library located at Via della Sapienza [it] #3 of the comune of Siena, in Tuscany, Italy.

In 1786 the library received works housed in the Santa Maria della Scala (Siena), among them the precious Byzantine lectionary Gospels (designated by ℓ 283 on the list Gregory-Aland) already part of the treasure of the same institution (X. IV.

Atop the entrance to the Historical Reading room of the library is a plaque with the six statutes of the old Accademia in Latin: In the 1990s reconstruction led to designation of a specific hall.

Some material of the Museo archeologico nazionale was transferred to the former monastery adjacent to Santa Maria della Scala.

Currently, the library's collection of printed books and manuscripts is estimated at over half a million units.