 | Jack Lemmon als Mel Edison |
 | Anne Bancroft als Edna Edison |
 | Gene Saks als Harry Edison |
 | Elizabeth Wilson als Pauline |
 | Florence Stanley als Pearl |
 | Maxine Stuart als Belle |
 | Ed Peck als Man Upstairs |
 | Gene Blakely als Charlie |
 | Ivor Francis als Psychiatrist |
 | Stack Pierce als Detective |
 | Patricia Marshall als Woman Upstairs |
 | Dee Carroll als Helen |
| Ketty Lester als Unemployment Clerk |
 | M. Emmet Walsh als Doorman |
 | F. Murray Abraham als Taxi Driver |
 | James McCallion als Mr. Cooperman |
| Fat Thomas als Bus Driver |
 | Arlen Stuart als Elevator Passenger |
 | Sylvester Stallone als Youth in Park |
| Alan DeWitt als Wayne Morgan |
| Harry Ray als Man with Dog |
| Lonnie Burr als Man on Street (uncredited) |
| Eddie Garrett als Elevator Passenger (uncredited) |
| Ben Lautman als NYU Student (uncredited) |
| Dave Michaels als Radio Newscaster (voice) (uncredited) |
 | Gary Owens als Radio Newscaster (voice) (uncredited) |
 | John Ritter als Elevator Passenger (uncredited) |
| Cosmo Sardo als Subway Passenger (uncredited) |
| Norman Stevans als Elevator Passenger (uncredited) |
 | Joe Turkel als Man Upstairs (voice) (uncredited) |
| Neil Simon | Theatre Play |
| Melvin Frank | Director |
| Joel Schumacher | Costume Design |
| E. Preston Ames | Art Direction |
| Harry Ray | Makeup Artist |
| Fred Williams | Makeup Artist |
| Sherry Wilson | Hairdresser |
| Bob Wyman | Editor |
| Melvin Frank | Producer |
| Marvin March | Set Decoration |
| Billie Owens | Sound Effects Editor |
| Arthur H. Pullen | Sound Effects Editor |
| Ed Scheid | Sound Effects Editor |
| John O. Young | Sound Effects Editor |
| Randy Nite | Sound Editor |
| Marvin Hamlisch | Original Music Composer |
| Philip H. Lathrop | Director of Photography |
| Hal Klein | Unit Production Manager |
| Howard Roessel | First Assistant Director |
| Bruce Satterlee | Second Assistant Director |
| Dennis J. Parrish | Property Master |
| Gene Lauritzen | Construction Coordinator |
| Mentor Huebner | Production Illustrator |
| Billy Mauch | Dialogue Editor |
| Al Overton | Sound |
| Neil Simon | Screenplay |
| Tex Rudloff | Sound |
| Arthur Bloom | Boom Operator |
| Jack C. Jacobsen | Sound Mixer |
| James Perdue | Sound Recordist |
| Lou Barlia | Camera Operator |
| Vinnie Gerardo | Assistant Camera |
| Carl Manoogian | Key Grip |
| Michael J. Harte | Wardrobe Supervisor |
| Thalia Phillips | Wardrobe Supervisor |
| Hope Williams | Script Supervisor |
| Alan DeWitt | Dialogue Coach |
| Pete Candoli | Musician |
| Donald Harris | Music Editor |
| Tommy Tedesco | Musician |
| Arnold Saint Subber | Other |
