In the suburban Hummingbird Hill, lawyer Harry King and his wife Tacey have trouble retaining a nanny for their three young, rambunctious boys: Larry and Tony, both of whom get into frequent mischief with the family dog Henry; and baby Roddy. When the latest in a string of servants (all women) quits, Tacey advertises for a replacement and hires Lynn Belvedere sight unseen. However, she discovers that Lynn Belvedere is actually a man upon his arrival, a mysterious one with many skills and achievements – and who declares himself to detest children. Nonetheless, the Kings reluctantly agree to a trial period during which Belvedere quickly wins over the boys. However, his mysterious nature intrigues both of their parents, and Harry becomes annoyed by his condescending attitude.

Before Harry King (Robert Young) goes on a business trip, his wife, Tacey King (Maureen O'Hara), agrees to take their son, Roddy (Roddy McCaskill), and sleep over each night at the home of their friends, fellow lawyer Bill Philby (John Russell) and his wife Edna (Louise Allbritton), just to squelch any possibility of scandal in the town over her remaining in the house with Lynn Belvedere (Clifton Webb). When one of the boys becomes sick late that night, Belvedere calls Tacey to come over for what is a stomachache. Nosy neighbor Clarence Appleton (Richard Haydn) notices the lights on and investigates, soon spreading scandalous rumors linking Belvedere and Tacey romantically. The gossip reaches Harry's boss Horatio J. Hammond (Ed Begley).

Tacey and Edna encounter Belvedere on his day off. Belvedere invites Tacey to dance. They are spotted dancing cheek to cheek by Appleton and his equally inquisitive mother, and the malicious rumors start again. This time, Harry is not so understanding. Insulted, Tacey quarrels with him, takes their youngest, and flies to her parents' home in Fort Worth, Texas.

In the meantime, we learn that Belvedere has spent the past few weeks secretly researching and writing a salacious account of the goingson among the residents of Hummingbird Hill. The published tome becomes a national bestseller, upsetting everyone in the community. Tacey rushes home and is reconciled with her husband. Hammond fires Harry and Bill, and then announces his decision to sue Belvedere, who is pleased, as he expects the publicity to increase sales of his already popular book. He hires Harry and Bill to defend him, then reveals the source of much of his information: none other than Clarence Appleton. The informant flees, with Hammond and others in hot pursuit. Despite his new fame, Belvedere agrees to keep his job as his successful book is only the first volume of what will become a trilogy.

A 1948 American Black & White comedy film directed by Walter Lang, produced by Samuel G. Engel, screenplay by F. Hugh Herbert, adapted from Gwen Davenport's novel "Belvedere" (1947), cinematography by Norbert Brodine, starring Robert Young, Maureen O'Hara, Clifton Webb, Richard Haydn, Louise Allbritton, Randy Stuart, Ed Begley, Larry Olsen, John Russell and Willard Robertson. Screen debut appearances of Betty Ann Lynn and Iris James.

Robert Young drives a 1941 Lincoln Zephyr 4door sedan.

Photographer Loomis Dean visited the set to photograph the filming for LIFE MAGAZINE and photographed Webb together with thenunknown actresses Laurette Luez and Marilyn Monroe, who do not appear in the film.

The film was originally titled "Belvedere", as the novel, but was changed.

Upon its release by 20th Century Fox in April 1948, Sitting Pretty became a boxoffice success. Although Clifton Webb received third billing here, Webb received critical praise for his performance of Belvedere, which spawned two Belvedere sequels, which he starred in. Webb received his third and final Oscar nomination, for Best Actor at the 1948 Academy Awards. It was his only nomination for lead actor (his two previous nominations were for supporting actor).

Webb's portrayal of Mr. Belvedere was the inspiration for Jonathan Harris' portrayal of Dr. Smith in the "Lost in Space" television series.

Webb also danced in the film, one of the rare chances he was able to showcase the dancing, singing, and comedic talents which made him popular on Broadway prior of his signing with Fox in 1944.

Pilots for a "Mr. Belvedere" television series were shot in 1959 with Hans Conried in the title role, and in 1965 with Victor Buono. The series finally made it to air on the ABC network as Mr. Belvedere (1985).

Clifton Webb's first incarnation as "Mr. Belvedere" is a riot. This is the film that really established Webb's long career at Fox in roles that seemed tailormade for his kind of pompous charm. Of course, it helps to have two of the screen's more likable younger actors, Young and O'Hara, as costars with Webb. An excellent family movie that deliberately avoids sappiness or extreme sentimentality. It's all for laughs and never fails to delight. This little charmer holds up remarkably well.