Classical 24 is a syndicated, satellite-delivered public radio service providing classical music to its carrying stations. It generally airs overnights on many non-commercial and a handful of commercial classical music stations. However, the service is operated 24 hours a day and is used by some stations during the day to augment their schedules. It was co-created by a partnership between Minnesota Public Radio and Public Radio International to fulfill the need for a comprehensive classic music service for stations to supplement their schedules. As part of this partnership, the service is produced by American Public Media and distributed by Public Radio Exchange. It began operation on December 1, 1995.
Unlike most mainstream classical music stations, Classical 24 adheres to a "clock" that typically consists of one or two short selections at the beginning of the hour, followed by a longer work such as a symphony, and then a short piece or two to close the hour. A brief pre-recorded "sound bite" interview with the composer, conductor or soloist of the next piece is sometimes played immediately prior to the piece, as an introduction.
Classical 24 also requires two breaks per hour during the day at around 20 and 40 minutes past (one per hour during the overnight Music Through the Night component) and a mandatory break at the top of the hour for announcements and station identification. The service also has a five-minute "cutaway" following this top of the hour break during the day for subscribers to air news programming (in many cases the standard NPR newscast, as a few NPR member stations use Classical 24); this time is filled with a short musical selection for affiliates who choose not to run any newscast.
Classical 24 employs live hosts around the clock instead of using voicetracking. To make the sound as "local" as possible, there are no identifications given to the listener that they are listening to Classical 24. Only the host's name is given. For stations to automate breaks, a special decoder must be purchased and used.
In 2000, the Minneapolis Star Tribune reported that the average selection on Classical 24 was 9.5 minutes, in contrast to then-rival WCAL's average selection length of 15 minutes. 
Minnesota Public Radio's FM flagship station for classical music, KSJN in Minneapolis, currently offers a full-time Classical 24 feed on its HD2 sub-channel. WNIU, broadcasting from Northern Illinois University in DeKalb, Illinois, is another full power FM that carries Classical 24 on a full-time basis. After November 2013, KUHA (now KXNG) in Houston (broadcasting from the University of Houston at the time) carried Classical 24 for a significantly increased portion of its schedule after discontinuing the use of local hosts during the daytime hours. Wisconsin Public Radio partially syndicates Classical 24 on their All Classical Network service, which airs on 13 different HD2 sub-channels throughout the State of Wisconsin. 
Classical 24 has three daypart-separated teams of ten different hosts which presents 4-hour/6-hour live air shifts:
The following presenters could also be heard on the network on a weekly basis in numerous short segments: