| One Is a Lonely Number | |
| Caption: | Original film poster |
| Director: | Mel Stuart |
| Producer: | Stan Margulies |
| Screenplay: | David Seltzer |
| Starring: | Trish Van Devere Monte Markham Janet Leigh Melvyn Douglas Jane Elliot Jonathan Lippe Mark Bramhall Paul Jenkins A. Scott Beach Henry Leff Dudley Knight |
| Music: | Michel Legrand |
| Cinematography: | Michel Hugo |
| Editing: | David Saxon |
| Distributor: | Metro-Goldwyn-Mayer |
| Runtime: | 97 minutes |
| Country: | United States |
| Language: | English |
One Is a Lonely Number (also known as Two Is a Happy Number) is a 1972 American drama film directed by Mel Stuart, and starring Trish Van Devere, Janet Leigh, and Melvyn Douglas. The screenplay, based upon the short story "The Good Humor Man" by Rebecca Morris, was written by David Seltzer.
The story follows Aimee Brower (Van Devere), who wakes and finds her husband has left her. After learning everything about why he did it, she then proceeds to put her life back together.