Three's a Crowd continued from Three's Company where in its final episodes, Vicky Bradford (Mary Cadorette) is introduced as a love interest of Jack Tripper (John Ritter), beginning in "Cupid Works Overtime". In the following two-part episode, "Friends and Lovers", Jack asks Vicky to marry him but she refuses and explains that although she loves Jack, she does not want to be married because she remembers when her father and mother got divorced and she explains that marriage scares her. However, Jack and Vicky eventually move to a new apartment together above his restaurant, the landlord of which is James Bradford (Robert Mandan), Vicky's wealthy father, who bought the building from Jack's former boss, Frank Angelino (Jordan Charney). James does not approve of Jack and he constantly tries to disrupt their relationship.
Other characters included E.Z. Taylor (Alan Campbell), Jack's "surfer dude" assistant chef at his bistro and Claudia Bradford (Jessica Walter), Vicky's mother and James' ex-wife.John Ritter as Jack Tripper
Mary Cadorette as Vicky Bradford
Robert Mandan as James Bradford
Alan Campbell as E.Z. Taylor
Jessica Walter as Claudia Bradford (recurring)
Three's Company had been based on the sitcom Man About the House, which aired on ITV in the United Kingdom from 1973 to 1976. When the series concluded in 1976, series producers Brian Cooke and Johnnie Mortimer devised two spin-offs of the series. The first spin-off was fashioned for actors Brian Murphy and Yootha Joyce who played the popular George and Mildred Roper on the series. The series, called George and Mildred, ran from 1977 to 1980, and followed the Ropers selling their apartment building and moving into a high class neighborhood, the comedy arising from the seemingly lower-class Ropers and their relationship with their higher-class neighbors. The second spin-off was written for Richard O'Sullivan, who played Robin Tripp (which would serve as the basis for Jack Tripper on Three's Company) and was named Robin's Nest, also the name of his restaurant on the series. Running from 1977 to 1981, the series followed Robin moving with his girlfriend into an apartment above the restaurant he ran, a situation which was frowned upon by her father.
Three's Company producers were anxious to capitalize on these spin-offs. In 1979, they had spun off Norman Fell and Audra Lindley into their own series The Ropers, based on George and Mildred, but it lasted only until 1980 after one and a half seasons. Three's Company's ratings remained high though. Executive producers Ted Bergmann and Don Taffner attempted to adapt the Robin's Nest series without John Ritter. A pilot for a series called Byrd's Nest was written, involving a young man living with his older girlfriend much to the chagrin of her father, who owned the building they lived in. The series was planned to be a spin-off from Three's Company and possibly a vehicle for Richard Kline, who played Larry Dallas on Three's Company, but ABC passed on the idea. However, as Three's Company entered its eighth season in 1983, ratings took a dive due to stiff competition from the new NBC series The A-Team. Realizing they had an aging show ABC okayed the development of a new series which was to be called Three's a Crowd.
Development and casting of the new series occurred in secret as Three's Company's eighth season progressed. Fellow cast members Richard Kline, Joyce DeWitt, Priscilla Barnes and Don Knotts were kept out of the loop. During a Christmas hiatus in late 1983 producers auditioned several female leads to play Jack's new love interest Vicky Bradford, and eventually decided upon Broadway actress Mary Cadorette. An embarrassing situation arose when Joyce DeWitt accidentally walked in on the auditions after coming to the studio to set up her dressing room as the holiday hiatus was coming to a close. DeWitt was then informed by the producers that Three's Company would end at the close of the season and would spin-off into Three's a Crowd with Ritter as star. DeWitt, who had been with the show from the beginning and weathered the highly publicized contractual dispute between Suzanne Somers, ABC and series producers, was hurt by the secrecy involved with the series ending and the spin-off. DeWitt and Barnes found it difficult to tape the rest of the season, as both actresses learned that their characters would conclude with the series finale. Kline and Knotts, however were offered an opportunity to have recurring roles on the spin-off; both actors declined the offer (Kline would make a guest appearance on the show in early 1985). Ironically, Somers reportedly unsuccessfully lobbied to reprise her Three's Company character Chrissy Snow as Jack's love interest in the spin-off. The sense of betrayal that DeWitt felt towards Ritter was short-lived and they reconciled by Three's Company's end.
In transitioning from Three's Company to Three's a Crowd, series producers decided to follow the plotline of the British series. Season eight of Three's Company drew to a close in a three-episode story arc. In the first of these episodes, Janet meets wealthy art collector Phillip Dawson. In the second episode she falls in love with him, while Jack meets and falls in love with stewardess Vicky Bradford. Her wealthy father, played by Robert Mandan, does not approve of the relationship. When first aired, this episode ended with the words "To be continued... next fall", and when rerun late in the summer, this was changed to "To be continued... next week". The last episode of Three's Company aired as an hour-long special that kicked off the 1984–1985 fall television season and set up the premise for Three's a Crowd. In the episode, Janet married Phillip, and Terri relocated to Hawaii. Jack and Vicky profess their love for one another, but Vicky turns down Jack's proposal of marriage, citing her fear of the institution after seeing her parents feud for her whole life. They instead move in together, in an apartment above Jack's Bistro. In the last scene, Jack and Vicky are spending their first romantic evening together in the new apartment, only to have Mr. Bradford accidentally barge in on them, explaining that he received the key from Jack's old boss Mr. Angelino, having just bought the building from him, becoming the couple's new landlord. The title card for Three's Company then appears over the screen with the word "COMPANY" zooming out, being replaced with "A CROWD".
Three's a Crowd employed most of the same writers, producers, and staff from Three's Company, but the new show's style was changed. While Jack was the lead star of Three's Company, it had an ensemble cast of three, with some ancillary characters. However, the new show was centered around Jack. Vicky, her parents, and E.Z. played supporting roles. The new show also employed even more slapstick comedy for John Ritter to exhibit. The events and characters of the previous show were not mentioned, except in a late season episode in which Larry Dallas appeared. He had moved to Bakersfield due to business downturns, and during his visit invited along "Greedy" Gretchen, who had often been mentioned on Three's Company. When rebuked by Jack, saying he was now living with a woman, she replied, "You're slowing down, Jack—you used to live with two women."
Three's a Crowd garnered only modest ratings, still competing with The A-Team. When the 1984–1985 television season finished, the show placed 38th in the Nielsen ratings. This put the show on the fence with ABC, since the show had enough of an audience to warrant renewal. However, when compared to Three's Company's ratings and The A-Team, which finished sixth for the season, ABC was tepid in committing to another season of Three's a Crowd. John Ritter was told that ABC would commit to a half-season of thirteen episodes to see how the series would place, although Ritter was reported as saying that he would not return to the show unless a full season was ordered. Finally, ABC decided instead to pick up Diff'rent Strokes, which had just been canceled by NBC.
Daytime reruns aired on ABC from September 23, 1985 to January 3, 1986, followed by another prime time run on USA Network. Some syndicated versions aired under the title Three's Company, Too, using an instrumental version of the theme song of Three's Company.
Six episodes of the series were aired on TV Land in September 2006, and four episodes were aired on WGN America in October 2008. The series began airing on digital broadcast network Antenna TV in June 2011 (as Three's a Crowd with its "Side by Side" theme song).