Director William Friedkin became interested in making a movie version of Harold Pinter’s play, The Birthday Party, in 1961, after seeing it performed by the San Francisco Actor’s Workshop, as stated in a 19 May 1968 LAT article. Having just directed his first film, a documentary called The People Vs. Paul Crump, Friedkin wrote to Pinter in hope of acquiring screen rights. The playwright did not respond; however, he did agree to a meeting with Friedkin years later, when it was set up by their shared talent agents, the 24 Mar 1967 LAT noted. After viewing Friedkin’s documentaries, Pinter gave him the rights to The Birthday Party despite having received bids from Joseph E. Levine and Carlo Ponti. They set the project up with Palomar Pictures International, Ltd., a subsidiary of ABC Pictures Corp., which offered financing and granted the filmmakers complete control over the project. In turn, Pinter was given cast approval and control of the script, which he insisted should not be altered whatsoever in shooting. The 19 May 1968 LAT claimed that Pinter “handpicked the cast himself,” including Robert Shaw, who had recently appeared in a film adaptation of Pinter’s 1960 play, The Caretaker.
       David Hemmings was initially cast in a lead role, the 20 Mar 1967 DV announced. He did not remain with the project.
       An item in the 31 May 1968 LAT cited a production budget of around $700,000. Robert Shaw’s salary was said to be $25,000, in addition to a profit percentage. Likewise, Friedkin and Pinter took low salaries in exchange for part ownership of the film.
       Rehearsals began the week of 11 Mar 1968, according to an item in the 20 Mar 1968 Var. Principal photography commenced later that month, on 25 Mar 1968, at Shepperton Studios in Shepperton, England, as stated in a 27 Mar 1968 Var production chart. The bulk of filming took place at a boardinghouse set built on a Shepperton soundstage, while a few exteriors were shot in the seaside town of Worthing, England, where Pinter had lived during “his acting days,” according to the 31 May 1968 LAT. On 5 Jun 1968, DV confirmed that filming had ended.
       The picture opened to generally positive reviews on 9 Dec 1968 at the Coronet Theatre in New York City. A Los Angeles, CA, benefit premiere followed on 14 Dec 1968 at the Beverly Canon Theatre, raising money for the Watts Writer Workshop. General release at the Beverly Canon took place on 17 Dec 1968.