The library has received a rare medieval Bible, dated back to 1240.
It was written in Oxford, England, and is a smaller version so monks and friars could carry it around.
It was purchased for $77,000 and is written in Latin.
There are less than 100 medieval Bibles in the U.S. Most Bibles from that era are in France or Italy.
Scott Gwara, a professor at USC, says the Bible looks as pristine as the day it was copied.