WXPN (88.5 FM) is a non-commercial, public radio station licensed to the Trustees of the University of Pennsylvania in Philadelphia, Pennsylvania, that broadcasts an adult album alternative (AAA) radio format, along with many other format shows. WXPN produces World Cafe, a music program distributed by NPR to many non-commercial stations in the United States. The station's call sign, which is often abbreviated to XPN, stands for "Experimental Pennsylvania Network". The broadcast tower used by WXPN is located at (40°2′19.7″N 75°14′12.8″W / 40.038806°N 75.236889°W / 40.038806; -75.236889), in the antenna farm complex in the Roxborough section of Philadelphia.

While the University of Pennsylvania has been involved with radio since 1909 when a wireless station was located in Houston Hall, WXPN itself first came into existence in 1945 as a carrier current station at 730 AM.

In 1957, it was granted a full license as a 10-watt college radio station at 88.9 FM in addition to their frequency of 730 AM. From then into the mid-1970s, WXPN was a student activity of the university and as it grew, the station initiated unique programming designs including one of the earliest freeform radio formats, Phase II, in the 1960s. Local DJ Michael Tearson got his start at WXPN in the late 1960s with a radio show The Attic. Tearson went on to replace Dave Herman at WMMR in 1970.

In 1975, a controversial broadcast on the talk show The Vegetable Report led to an obscenity complaint with the FCC, which found the charges serious enough to decline renewal of the broadcast license. This incident (December 1975) marked the first time the FCC pulled a license on grounds of obscenity. But a citizen's group organized to petition the FCC to consider XPN's unique service, and with a pledge from Penn to create positions for professional staff to run the station, the FCC allowed the license to renew.

With this new staff of five managers, WXPN became a steady fountain of high-quality folk, jazz, new and avant-garde music and public affairs programming produced by a combination of station alumni and community volunteers, with little to no student involvement. Veterans of WXPN that have gone on to notable achievements in other areas include Broadway producer and director Harold Prince, the station's first program director, NBC News correspondent Andrea Mitchell, its former news director, jazz producer Michael Cuscuna, a former DJ, and Echoes producers John Diliberto and Kimberly Haas, former producers of Diaspar, and other WXPN shows.

Shows that have been staples on XPN since the 1970s include The Blues Show with Jonny Meister (Saturday nights), Sleepy Hollow (Saturday and Sunday morning quiet music shows), Star's End (ambient and space music Saturday night/Sunday morning) and Amazon Country (lesbian-oriented music and programming on Sunday evening). WXPN also broadcasts the Folk Show on Sunday evening, which started at WHAT-FM in 1962 and continued on WDAS-FM, WMMR, WIOQ and WHYY-FM but moved to WXPN in the 1990s when WHYY changed to a talk format.

In 1986, the station qualified for membership in the Corporation for Public Broadcasting and began the legal process to move from 88.9 to 88.5 on the FM broadcast band in order to increase signal coverage. Beginning the late 1980s, the programming and personnel were shifted from its diverse volunteer voice to full-time salaried programmers. Penn student radio activity is currently carried out on WQHS.

In 1988, WXPN started Kids Corner, a daily interactive radio show for kids hosted by Kathy O'Connell. Kids Corner has won numerous awards, including the Peabody Award and the Armstrong Award.