Carr is the first of the Von Trap kids to die. She died from a disease called "dementia".
Dementia is not a specific disease. It's an overall term that describes a wide range of symptoms associated with a decline in memory or other thinking skills severe enough to reduce a person's ability to perform everyday activities.
She played the role Liesl Von Trapp at the age of 21 and sang one of the songs in the movie known as 'I Am Sixteen Going On Seventeen'.
She wrote two books about her experiences, titled Forever Liesl and Letter to Liesl.
Ms Carr's spokesman Harlan Boll said she died of complications from a rare form of dementia in Los Angeles.
After Carr left the movie business, she started a design company called Charmian Carr Design.
She is survived by daughters Jennifer and Emily, four grandchildren Emma, Derek, William and Tucker, four siblings Sharon, Darlene, Michael and Brian
20th Century Fox paid tribute to the star, writing on Twitter: "The Sound of Music lost a beloved member of the family w/ the passing of Charmian Carr. She will be forever missed".