The MPRC' s holdings consist of over a thousand hours of recordings. These are a11 archive-recordings, both audio and video, that is recordings that have not been made for commercial purposes; they cannot be purchased or borrowed. They are of public performances and conversations with performers, dating from the early 1930s to the present time, which at the time of going to press cover aperiod from 1933 to 1995. Nearly a11 these recordings do not exist in other archives. The performances are preserved without any editing. Recordings continue to be added to the library.