Billy Wilder always worked best with a script collaborator. He had created several successful films in the 1930s and 40s with Charles Brackett before they ended their association. It wasn't until the mid-50s before Wilder found another writer with mutual collaborative skills. The quiet, introverted I.A.L. Diamond had a dramatically different personality from the outgoing Wilder. But they shared a common European immigrant background, the same dry sense of humor, and an interest in many of the same themes and characterizations, such as the use of tangled webs of deception. They had two successful pictures under their belt - Love in the Afternoon (1957) and Some Like It Hot - when they started this one.

Wilder and Diamond were so impressed with Jack Lemmon's performance in their first film with the actor, Some Like It Hot, they decided in the first month of production on that picture that "this was not to be a one-shot thing with Jack. We wanted to work with him again, and while Some Like It Hot was still in the works, we got underway with the planning of another one, The Apartment."

Lemmon said he signed onto The Apartment after Wilder told him the story but before he ever saw a line of the script. "I'd have signed even if he said he was going to do the phone book," the actor noted.

"Billy's scripts are amazing," Lemmon later said. "They take a year and a half to write and everything's in them, but everything. He sees scripts. A script is to be played, not read. So if something doesn't look right in action, he'll change it."

The part of Sheldrake, the company boss having an affair with the elevator operator, had been written with Paul Douglas in mind. Two weeks before the start of production, Douglas died of a heart attack. Wilder asked Fred MacMurray, who he had directed in Double Indemnity (1944), to step into the role.

MacMurray played mostly comic and light leading man parts for most of his career. Any trepidation he may have had about playing a heel in this picture were put to rest by the fact that he had done some of his best work in a dark, serious part in Wilder's Double Indemnity.

by Rob Nixon