WJZ-TV (channel 13) is a television station in Baltimore, Maryland, United States, serving as the market's CBS outlet. It is owned and operated by the network's CBS News and Stations division, and maintains studios and offices on Television Hill in the Woodberry section of Baltimore, adjacent to the transmission tower it shares with several other Baltimore broadcast outlets.

The station first signed on the air on November 1, 1948, as WAAM, becoming the third television station in Baltimore behind WBAL-TV (channel 11) and WMAR-TV (channel 2), all within just over a year. The station was originally owned by Radio-Television of Baltimore Inc., whose principals were Baltimore businessmen and brothers, Ben and Herman Cohen. Channel 13 was originally an ABC affiliate, the network's fifth outlet to be located on the East Coast. It carried a secondary affiliation with the DuMont Television Network until its closure in 1956. Both affiliations moved from WMAR-TV, which became an exclusive CBS affiliate.

On the station's second day of operations, WAAM broadcast the 1948 presidential election returns and various entertainment shows, remaining on the air for 23 consecutive hours. Channel 13 has been housed in the same studio facility, located near Druid Hill Park on what was then known as Malden Hill (now known as Television Hill), since the station's inception; the building was the first in Baltimore specifically designed for television production and broadcasting. As a DuMont affiliate, WAAM originated many Baltimore Colts games for the network's National Football League coverage.

The Westinghouse Electric Corporation purchased WAAM from the Cohen brothers in May 1957. Westinghouse then took control of the station in August of that year, and the following month, the station changed its callsign to WJZ-TV. The WJZ call letters had previously resided on ABC's flagship radio/television combination in New York City, which changed its calls to WABC-AM-FM-TV in 1953. However, Westinghouse's history with that set of call letters went back even further, as it was the original owner of WJZ radio, the flagship station of NBC's Blue Network, which would eventually become ABC.

All of Baltimore's television stations at the time had fairly short transmission towers in the medium's early years; channel 13's original tower was located next to the station's studios. In 1959, WJZ-TV collaborated with WBAL-TV and WMAR-TV to form a joint venture to build the world's first three-pronged candelabra tower. Constructed behind the WJZ-TV studios and opposite the original channel 13 tower, it was the tallest free standing television antenna in the United States at the time of its completion. The new tower significantly improved channel 13's signal coverage in central Maryland, and also added new viewers in Pennsylvania, Delaware, Washington, D.C., and Virginia.

WJZ-TV nearly lost its ABC affiliation in 1977, when the network briefly pursued WBAL-TV just as ABC became the most-watched broadcast network (in prime time) in the United States for the first time. However, WBAL-TV declined the ABC affiliation offer due to ABC's last-place network evening newscast offerings of the time (a situation that would improve in ensuing years), keeping ABC on channel 13.

In June 1994, ABC agreed to an affiliation deal with the broadcasting division of the E. W. Scripps Company, which resulted in three of Scripps' television stations—WMAR-TV in Baltimore, WFTS-TV in Tampa and KNXV-TV in Phoenix—becoming ABC affiliates. ABC agreed to the deal as a condition of keeping its affiliation on Scripps' two biggest stations, WXYZ-TV in Detroit and WEWS in Cleveland. Both stations had been heavily courted by CBS, which was about to lose two of its longtime affiliates—WJBK and WJW—to Fox. ABC was reluctant to include WMAR, then an NBC affiliate, in the deal; it had been a ratings also-ran for over 30 years while WJZ-TV was one of the strongest ABC affiliates in the nation. However, not wanting to be relegated to UHF in two markets with few viable choices for a new affiliate, ABC opted to end its 46-year affiliation with channel 13 and move its affiliation to channel 2.

Group W felt betrayed by ABC after so many years of loyalty, as channel 13 had been ABC's longest-tenured affiliate at the time (a distinction that now belongs to WJLA-TV in Washington). As a safeguard, it began to shop for an affiliation deal of its own. In the early summer of 1994, the station was approached by NBC to negotiate an affiliation agreement with the network to replace WMAR as its Baltimore affiliate. Channel 13 station management would later turn the offer down. Instead, one month later, Westinghouse agreed to a long-term affiliation contract with CBS, resulting in WJZ-TV, as well as WBZ-TV in Boston and KYW-TV in Philadelphia, switching to CBS (Westinghouse's two other television stations, KDKA-TV in Pittsburgh and KPIX-TV in San Francisco, were already CBS affiliates). The affiliation switch, the second in Baltimore television history, occurred early on the morning of January 2, 1995. Though ABC's affiliation contract with channel 13 did not expire until January 1995, starting in 1994, all CBS programs preempted by WBAL-TV would air on WJZ-TV. The last ABC prime time program to air on channel 13 was the made-for-TV movie A Dangerous Affair, which was broadcast at 9 p.m. Eastern Time on January 1, and the final overall ABC program to air on channel 13 was the January 2 edition of ABC World News Now. As a result, channel 13 became the third station in Baltimore to affiliate with CBS. The network had originally affiliated with WMAR-TV in 1948 before moving to WBAL-TV in 1981. Almost by default, the 1995 switches saw the NBC affiliation return to WBAL-TV after a 14-year absence.