As the young actress told Life in 1971: My father's family came from Tuxedo Park, and they offered to take us kids and pay for our education, on the condition that Mama never see us again.

She guest starred on The Red Skelton Hour in "Appleby: The Big Producer" (1959) and on 77 Sunset Strip (1959) and The Millionaire (1960).

At Fox, she played Joy, a free-spirited university student in High Time, starring Bing Crosby and Fabian Forte.

She sang a love song to Fabian in the season opener of NBC's The Dinah Shore Chevy Show on October 9, 1960.

Four weeks later, on November 13, Weld returned to the network as a guest star in NBC's The Tab Hunter Show.

[17] For Fox, Weld had a supporting role in the sequel Return to Peyton Place (1961), in the part played by Hope Lange in the original.

[18] Fox also used her as a guest star on Follow the Sun ("The Highest Wall") and Adventures in Paradise ("The Velvet Trap").

On November 12, 1961, she played a singer, Cherie, in the seventh episode of ABC's television series Bus Stop, produced by Fox, with Marilyn Maxwell and Gary Lockwood.

Then she starred along with Jackie Gleason and Steve McQueen in Soldier in the Rain, written by Blake Edwards from a novel by William Goldman, but the film was only a minor success.

[21] She won excellent reviews for a February 7, 1962, episode in the Naked City, "A Case Study of Two Savages", adapted from the real-life case of backwood killers Charles Starkweather (played by Rip Torn) and Caril Ann Fugate, (depicted as the character Ora Mae Youngham, played by Weld), Starkweather's young bride, on a homicidal spree ending in New York City.

[22] She guest starred on Route 66 in "Love Is a Skinny Kid" (1962), Ben Casey in "When You See an Evil Man" (1962), and The Dick Powell Theatre in "A Time to Die" (1962) and "Run Till It's Dark" with Fabian (1962).

In 1963 Weld guest-starred as Denise Dunlear in The Eleventh Hour, in the episode "Something Crazy's Going on in the Back Room" alongside Angela Lansbury.

In 1964 she appeared in the title role of the episode "Keep an Eye on Emily" on Craig Stevens's CBS drama, Mr. Broadway.

She appeared with her former co-star Dwayne Hickman in Jack Palance's circus drama The Greatest Show on Earth on ABC, in separate episodes.

Weld appeared in 1965 in the successful Norman Jewison film The Cincinnati Kid, opposite Steve McQueen.

There was some controversy when she refused to meet the local governor at a fund-raiser for hurricane victims, jumping out of a car in view of 70,000 people.

Weld got a star role in Lord Love a Duck (1966), with Roddy McDowall, Ruth Gordon, and Harvey Korman.

She followed it playing Abigail in a TV adaptation of The Crucible (1967), opposite George C. Scott and Colleen Dewhurst.

Around this time, Weld became famous for turning down roles in films that succeeded at the box office, such as Bonnie and Clyde, Rosemary's Baby, True Grit, Cactus Flower, and Bob & Carol & Ted & Alice.

[20] The films Weld did make included I Walk the Line (1970), opposite Gregory Peck; A Safe Place (1971), co-starring Jack Nicholson and Orson Welles and directed by Henry Jaglom, and Play It as It Lays (1972), again with Perkins, for which she was nominated for a Golden Globe Award.

Weld attracted attention as the favored, out-of-control Katherine in Looking for Mr. Goodbar (1977)—packing into her short screen time an orgy, a divorce, a lot of alcohol, and two abortions—and was nominated for an Academy Award for Best Supporting Actress;[20] later she appeared in Who'll Stop the Rain (1978) opposite Nick Nolte; and the ensemble satire Serial (1980).

In 1984, she appeared in Sergio Leone's gangster epic Once Upon a Time in America, playing a jeweler's secretary, who is in on a plan to steal a shipment of diamonds.

In 1993, she played a police officer's neurotic wife in Falling Down, starring Michael Douglas and Robert Duvall.

[27] On October 18, 1985, she married Israeli concert violinist and conductor Pinchas Zukerman, becoming stepmother to his daughters Arianna and Natalia.

[37] Weld and then-husband Zukerman purchased 74 Surfside Ave in 1990 from the estate of Norman Kean, who produced the long-running Broadway show Oh!

[38] Although the Montauk residence was not a crime scene, Weld later struggled to find a buyer for the property due to its murder-suicide connection.

Sweet's greatest hits compilation Time Capsule features photos of Weld on the front and back covers.