A seven-story wing was built to the south of the original building in 1959 to a design by Collens, Willis & Beckonert, and was renamed for Martin Luther King Jr. in 1985.

[20] Fosdick stated he would accept the minister position on the conditions that the church would move to Morningside Heights, follow a policy of religious liberalism, remove the requirement for members to be baptized, and become nondenominational.

[29] Morningside Heights, where the new church was to be located, was being quickly developed as a residential neighborhood surrounded by numerous higher-education institutions, including Union Theological Seminary and International House of New York.

In exchange, Riverside Church received a small plot to its south, allowing for the construction of the chapel and a proposed cloister passage to Claremont Avenue.

Rockefeller offered to exchange his neighboring apartment building at 122nd Street and Claremont Avenue for the lots south of the church, which were owned by the seminary.

By 1939, the church had more than 200 staff in both part-time and full-time positions, and over 10,000 people a week were attending its social and religious services, athletic events, and employment programs.

[84] In 1956, halfway through McCracken's tenure, the church conducted an internal report and found the organizational structure was disorganized and that most staff did not feel any single person was in charge.

[70][87][88] A 15-foot (4.6 m) dummy antenna had been placed on top of Riverside Church's 392-foot (119 m)-tall carillon earlier that year to determine whether it could be used by Columbia University's radio station, WKCR (89.9 MHz FM), despite strong opposition from parishioners and the local community.

[91] Rockefeller purchased the Stone Gym, an existing Union Theological Seminary building southeast of the original church, and reopened it as a community facility in April 1962 after a five-year renovation.

[98][99] Following a 1972 metropolitan mission study, several ministries aimed toward ameliorating social conditions in the New York City area were formed at Riverside Church.

[104] At this point, the congregation's size had been declining for several years but after Coffin's selection as senior minister, membership increased to 2,627 by the end of 1979, and total annual attendance for morning services rose from 49,902 in 1976 to 71,536 in 1978.

[116] The plan included a major addition on Riverside Church's eastern side, consisting of the relocation of the Claremont Avenue entrance, paving of the forecourt, reconfiguration of the cloister lobby, and construction of a seven-story building over the gymnasium.

This plan was controversial among congregants, some of whom petitioned the New York City Landmarks Preservation Commission (NYCLPC) to designate the church to prevent the alteration of the original appearance of the Claremont Avenue entrance.

[43][45][53] Pelton and Collens chose a Gothic architectural style for Riverside Church's exterior; by contrast, the internal structure incorporates modern curtain walls and a steel frame.

[140][144] The writers of the 1939 WPA Guide to New York City said the tower's features make the "building itself seem smaller than it is, so that its scale is scarcely impressive, even when seen at close range".

[134] The nave's interior contains a finish of Indiana limestone, the ceilings of its vaults are lined with Guastavino terracotta tiles, and its floor is made of marble.

[134][158][159] Pointed arches resting on piers that contain engaged columns support each of the clerestory bays and serve as the bases for the ribs under the vaulted ceiling.

[158] The tiles above the chancel and the nave's northernmost two bays are brown because a sealant that was applied in 1953 to increase the organ's acoustical reach has turned yellow over time.

The design, which was described by architectural historian Andrew Dolkart as "earlier than Gothic", is intended to give the impression the rest of the sanctuary was built after the chapel.

[178] The Martin Luther King Jr. (MLK) Wing is a seven-story annex south of the main structure and facing 120th Street along the southern boundary of the plot.

[182] The building was known as the South Wing until 1985, when it was renamed for civil rights leader Martin Luther King Jr.[92][116] The facade is clad with Indiana limestone, the foundation is made of stone and concrete, and the structure is supported by a steel frame.

[178] The basement, first and second floors of the western facade contains eight architectural bays, each with one small lancet window, which are recessed between projecting buttresses and below a set of arches.

[183] The northern arm of the MLK Wing's first floor includes the South Hall Lobby, which has a two-story-high coffered ceiling that is supported by a pointed-arch arcade and its walls are made of gray plaster.

[186] The gala concert celebrating the opening of this console included a work for two organs Signs in the Sun commissioned for the event from Daniel Pinkham.

[191] Past organists at the Riverside Church include Virgil Fox (1946–1965),[192] Frederick Swann (1957–1982),[193] John Walker (1979–1992),[194] Timothy Smith (1992–2008),[195] and Christopher Johnson (2009–2021).

[148] The columns framing the door jambs beneath the archivolts are decorated with capitals and gargoyles at the top and bottom, and a single figure in the middle.

[134][147] When Riverside Church was completed, there was controversy over the inclusion of Einstein, a living Jewish man, because the other figures represented people who had since died.

[160] It depicts influential figures including the composer Johann Sebastian Bach, the U.S. president Abraham Lincoln, the artist Michelangelo, the social reformer Florence Nightingale, and the author Booker T.

A recorded sermon from Riverside Church airs on the station from 5:00 to 6:00 a.m. on Sunday mornings, as part of WLTW's non-music public affairs programming.

[239][240] Speakers at Riverside Church have also included theologians Paul Tillich, who taught nearby,[241] and Reinhold Niebuhr;[237] civil-rights activists Cesar Chavez[237] and Desmond Tutu;[237][242] Cuban president Fidel Castro;[243] the 14th Dalai Lama;[123] and Abdullah II of Jordan.