WAMU (88.5 FM) is a public news–talk station that services the greater Washington, DC metropolitan area. It is owned by American University, and its studios are located near the campus in northwest Washington. WAMU has been the primary National Public Radio member station for Washington since 2007.

WAMU began as an AM carrier-current student radio station, signing on July 28, 1951, on 1200 kHz, before shifting to 590 kHz in March 1952 and 610 kHz in November 1952. Although carrier-current stations are not granted a license or call sign by the FCC, it used "WAMU" as a familiar form of identification. The station aired a wide range of student-produced programming including music, news, sports, radio dramas, and debates. The station was heralded as a rebirth of the university's prior radio station, WAMC, which operated on 590 kHz for about two years starting on January 15, 1947, broadcasting with a 50-watt transmitter as part of a plan to offer a full range of radio and television courses at American University. WAMC's operations were sporadic and the station suffered interference from a 50,000-watt station broadcasting from Mexico on the same frequency, but it finally went off the air after station equipment was stolen in 1950.

Throughout the late 1950s, students and faculty involved with WAMU-AM pushed to create an FM station that could reach beyond campus and serve Washington, D.C., as a whole. In late 1960, the university received a non-commercial FM broadcasting license, and WAMU made its first FM broadcast on October 23, 1961, on 88.5 MHz using a 4,000-watt second-hand transmitter acquired from WGBH in Boston. Although it was not strictly necessary as the AM carrier-current station's call sign was not official, the FM station took the suffixed call sign "WAMU-FM" to differentiate itself. The station dropped the -FM suffix in 1981.

WAMU-FM station was established as an "education station" operated by the university, not as a student-run station. Despite this about 75 AU students, many of whom also worked at the carrier-current station, produced local programming for WAMU-FM. In its first year of operation, WAMU simulcast the same programming, which included educational programs, dramas, and classical music, on AM and FM for three hours each evening.

From its inception as a student-run station, WAMU provided public affairs and educational programming. With the launch of its FM service in 1961, WAMU joined the nascent National Educational Radio Network, a predecessor to NPR. In 1971, the station was a founding member of National Public Radio.

In 1967, WAMU-FM began programming bluegrass music which, in its heyday on the main channel, included the Lee Michael Demsey Show and the Ray Davis Show and weekends included Stained Glass Bluegrass and West Virginia Public Radio's Mountain Stage. The station hosted an annual bluegrass concert at Fairfax High School, as well as the yearly "Pickin' in the Glen" concert, featuring performers such as Alison Krauss, Tony Rice, the Gibson Brothers, the Lewis Family, Hot Rize, and Red Knuckles and the Trailblazers. However, starting in the late 1990s, the station began paring back its on-air bluegrass programming in favor of news/talk programming. In summer 2001, the station fully transitioned its weekday programming to all news and public affairs from various providers including NPR, PRI, APM and the BBC World Service, and in September 2007 the station removed the last of its bluegrass programming from its main channel, shifting it all to the HD2 subchannel.

On May 7, 2004, WAMU-FM began digital broadcasting using the HD Radio standard and launched the Americana-music station Bluegrass Country on its HD2 subchannel. The station also operated for several years an HD3 service, WAMU-3, broadcasting a mix of talk and music programming, including simulcast programming from Towson University's WTMD.

Also in 2004, the prominent Washington journalist Ellen Wadley Roper left WAMU a $250,000 bequest, the largest gift in the station's history.