WLIW (channel 21) is a secondary PBS member television station licensed to Garden City, New York, United States, serving the New York City television market. It is owned by The WNET Group alongside the area's primary PBS member, Newark, New Jersey–licensed WNET (channel 13); two Class A stations, WNDT-CD (channel 14) and WMBQ-CD (channel 46, which shares spectrum with WLIW); and WLIW-FM (88.3) in Southampton. Through an outsourcing agreement, The WNET Group also operates New Jersey's PBS state network NJ PBS and the website NJ Spotlight.

WLIW and WNET share studios at One Worldwide Plaza in Midtown Manhattan with an auxiliary street-level studio in the Lincoln Center complex on Manhattan's Upper West Side. WLIW's transmitter is located at One World Trade Center; the station also maintains a production studio at its former transmitter site in Plainview, New York. WLIW's multiplex is New York's high-power ATSC 3.0 (NextGen TV) television station and also broadcasts WMBQ-CD.

WLIW was established in 1969 as the first television station on Long Island. Originally operated on a tight budget, the station had no permanent studio facilities for nearly a decade. In the 1980s and 1990s, increasing cable television coverage led to the expansion of WLIW into a regional service that was the smaller competitor to WNET, the nation's largest public TV station, and the station increased its own programming efforts. However, some critics felt that this shift deemphasized the station's Long Island identity. In 2003, WLIW and WNET merged, completing an 18-month process. As part of the WNET Group, WLIW maintains a separate vice president and general manager, Diane Masciale, who is in charge of the entire group's locally oriented television production.[2]