Jacqueline Susann's Once Is Not Enough is a 1975 American romance film, directed by Guy Green, starring Kirk Douglas, Alexis Smith, David Janssen, George Hamilton, Brenda Vaccaro, Melina Mercouri, and Deborah Raffin.

Accustomed to a lavish lifestyle, Mike has pampered his daughter, January, providing her with an expensive education in Europe and everything else money can buy.

Needing capital, Mike enters into a loveless marriage with Deidre Milford Granger, one of the world's wealthiest women.

Deidre attempts to draw January into a relationship with her cousin David Milford, a ladies' man who also usually gets his own way.

Unsure what to do with her life, January is advised by an old friend, Linda Riggs, now a magazine editor, to write a book.

Realizing that nothing is perfect in life, not even in its own way, January is left alone wandering Manhattan after dark but with hope that tomorrow will be a better day.

Guy Green was hired to direct the film, according to one Paramount executive, because he "might give it class".

Green wanted Dick Van Dyke to play the role of Mike Wayne.