As widowed mother Shirley and her irrepressible son Keith Partridge, Jones and Cassidy played lightly fictionalized versions of themselves - two entertainers in a family full of them that decides to stick together and seek success as a group. Actor-musician Marie Osmond sent her condolences sharing images of covers from teen magazine in which he shared with her brothers.
Cassidy began his acting career onstage, making his Broadway debut in the short-lived musical The Fig Leaves Are Falling, which closed after 21 performances in January 1969.
The single's meteoric rise, coupled with Cassidy's global popularity as one of the biggest teen idols of the 1970s, led to a hugely successful solo career that drew sell-out crowds in major arenas across the world.
Many remembered Cassidy's impact on their lives. He posed naked for Rolling Stone in 1972, when he both confided that he had dropped acid as a teenager and smoked pot in front of the magazine's reporter as he watched an episode of The Partridge Family while mocking his own acting.
Even while The Partridge Family was still in primetime, Cassidy anxious that he was mistaken for the wholesome character he played.
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Cassidy maintained an exhausting schedule during the show's run, filming during the week and performing live shows over the weekend, but had plenty of time to indulge himself. "It was nuts", Cassidy said. I've had to sing when I was hoarse....
"I'll feel really good when it's over", he said, adding: "I have an image of myself in five years". I'm living on an island. I see my skin very brown and leathery, with a bit of growth on my face. "I have some grey hair already". Almost 800 hysterical fans had to be carried out of the arena, and 14-year-old Bernadette Whelan was crushed to death by the crowd.
It was 1970, with the turbulent late 1960s of the Vietnam War, race riots, psychedelia, Woodstock and Altamont barely past, when Cassidy got the lead role on the show, overseen by the same producers as The Monkees.
"So many people come up to me and talk to me about the impact it [the show] had", he told Arsenio Hall in 1990.
David Cassidy later embraced his teen idol status, telling USA Today in 1993, "I used to think of The Partridge Family as an albatross, but it's given me wings".