Diane Hall was born on January 5, 1946, in Los Angeles, California. The daughter of a civil engineer and a struggling photographer, Diane's early years were comfortable and ordinary. She spent her days engaged in typical American pursuits, never giving any thought to chasing a career in the entertainment industry. That all changed, however, after Diane watched her mother enter and eventually win the title of Mrs. Los Angeles at a pageant for homemakers. The grandiose, theatrical nature of the event opened Diane's eyes to the pleasures of a life spent in the spotlight.

She began tentatively exploring her creative side in high school, where she participated in various drama clubs and even took on a central role in a production of Tennesse Williams' A Streetcar Named Desire. After graduation, Diane enrolled in acting courses at two nearby colleges, though she didn't last more than a year before she decided to move to New York City.

Almost immediately after arriving in Manhattan, Diane discovered that there was already a Diane Hall registered with the Actors' Equity Association and subsequently changed her surname to Keaton. She spent her early years in New York City honing her craft and appearing on local stages with a nightclub act and, in 1968, she finally caught a break after becoming an understudy on the Broadway production of Hair.

She followed that up with a series of appearances in long-since-forgotten movies and television shows, including 1970's Lovers and Other Strangers (her debut) and 1971's Men of Crisis: The Harvey Wallinger Story.

In 1971, Diane Keaton auditioned for a pivotal role in a new gangster film from up-and-coming director Francis Ford Coppola. She successfully won the part, and The Godfather definitively proved that Diane has what it takes to hold her own opposite legends like Al Pacino and Marlon Brando. It was also around that time that Diane first encountered a young writer/director named Woody Allen.

Having appeared in the stage version of Play It Again, Sam (which Woody wrote and starred in), Diane soon found herself being invited to star in such legendary comedies as 1973's Sleeper, 1977's Annie Hall (for which she won her first and only Oscar) and 1979's Manhattan. In fact, the character of Annie Hall is said to be based loosely on Diane herself (Diane and Woody were dating at the time and her nickname is Annie).

Diane and Woody's relationship ended in the late '70s, and she soon began going out with legendary ladies man Warren Beatty. Their union crossed over into work after Warren cast Diane in his sweeping historical epic Reds (1981), though the two broke up shortly following the release of the film. Diane spent much of the '80s appearing in critically acclaimed but financially disappointing films, such as 1982's Shoot the Moon, 1984's Mrs. Soffel (opposite a young Mel Gibson), and 1986's Crimes of the Heart. She bounced back in 1987 with a starring role in the workplace comedy Baby Boom, and followed that up with 1990's trilogy-ending Godfather III.

After experiencing a string of hits, including 1991's Father of the Bride, 1993's Manhattan Murder Mystery and 1996's The First Wives Club, starring Goldie Hawn, Diane decided that the time was right to make her theatrical debut as a director. Though she was no stranger to the world of filmmaking, Diane helmed a lauded television movie in the early '90s. 1995's Unstrung Heroes established Diane as a gifted and surprisingly subtle director in her own right (the movie was eventually nominated for an Oscar).

Diane's love life in the '90s was apparently nonexistent, and the actress decided to plow ahead with plans to form a family on her own. She has since adopted two children (daughter Dexter and son Duke).

Professionally speaking, Diane was as busy as ever in the following years, taking on both dramas (1996's Marvin's Room and 1999's The Other Sister) and comedies (2003's Something's Gotta Give and 2005's The Family Stone), and with three 2007 films, including the Mandy Moore and Piper Perabo flick Because I Said So.