Shirley Jones Turns 90! Sons Shaun Cassidy, Patrick Cassidy and Ryan Cassidy Celebrate “Partridge Family” Star

"Simple things mean the most to her," Shaun Cassidy said of his mom

Shirley Jones marked her milestone 90th birthday with her kids and grandkids by her side.

The Oscar-winning actress and The Partridge Family icon hit the big 9-0 on Sunday, March 31 — and celebrated in an intimate party in a snowy mountain getaway.

Jones' son Shaun Cassidy, 65, documented the events on social media, sharing a photo of him and his brothers — Patrick Cassidy, 62, and Ryan Cassidy, 58 — posing with the Hollywood legend.

"Happy 90th birthday to Miss Pittsburgh!" he captioned the post, with a nod to Jones' beauty pageant win back in 1952. "What an incredible night."

For her big day, Jones was decked out in a bedazzled blue tracksuit. She wore a golden sash that read "90 & Fabulous," and donned a silver tiara with the number "90" in the center.

Related: Inside '70s Teen Idol Shaun Cassidy's Return to Performing: 'Something I Never Thought I'd Do Again' (Exclusive)

Shaun also posted a throwback picture of Shirley, taken on her 21st birthday by his grandfather, Paul Jones.

"The flowers were gifts from fans who’d recently discovered her — and her glorious singing voice — in the motion picture Oklahoma," he explained in a long note on his website. "Mom would soon begin shooting her second film for Rodgers & Hammerstein, Carousel, and in a few years, she’d win the Academy Award for a dramatic turn in [1960's] Elmer Gantry."

Of course, while the public knows Shirley from those films — and for her extensive work on television, including in The Partridge Family — Shaun said that "to us, her family, Shirley Jones has always simply been mom."

"In a journey full of dramatic highs and lows, mom has always been an optimist and a lover of life," he wrote, praising "this small-town girl from Western Pennsylvania, who grew up to become a movie star but who never acted like one."

"Simple things mean the most to her: family, friends, nature, animals, laughter, sing-a-longs at the piano, a dry martini. Not necessarily in that order," he joked.

Related: Celebrities Over 90 Years Old, Then & Now

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Her birthday celebrations were an opportunity for the whole family to "gather to share all of these things and more with mom, grateful to have her with us, and blessed by her good health," Shaun said. "Happy Birthday Mom. Thanks for always offering us ground in an uncertain world, and for inspiring so many with your talent and heart. I love you."

Patrick also spoke out about the birthday celebration, explaining in an Instagram post that the party was attended by all of their "children, wives, girlfriends and family."

"Each person from the youngest granddaughter to the oldest son told a story about what this incredible woman meant to them," he recalled of the event. "It was one of the most beautiful, emotional, personal moments all of us could’ve ever asked for."

"Happy Birthday Shirley Jones," Patrick wrote. "A mother, a grandmother, a mother-in-law, a person that has meant so much to so many. But most of all to us, your family. We Love You ❤️🎂 ."

Shirley was married to Jack Cassidy from 1956 until 1975, the pair having sons Shaun, Patrick and Ryan together. She was also mom to stepson David Cassidy, who died from organ failure in November 2017 at the age of 67.

After divorcing Jack, Shirley married actor and comedian Marty Ingels in 1977. They remained together until Ingels' death in October 2015 (though Shirley filed and withdrew a divorce petition in 2002). Jack, meanwhile, died in a 1976 fire at the age of 49.

The actress spent four years playing matriarch Shirley Partridge onThe Partridge Family, the beloved ABC musical sitcom loosely based on The Cowsills, the real-life musical family. The show followed a young widowed mother and her five children who tour the country with their singing group in a signature painted bus.

Related: Whatever Happened to 'The Partridge Family' ? A Look Back at the Stars of the '70s Sitcom

Shirley famously accepted the role after turning down the part of Carol Brady on The Brady Bunch. And while the show earned her a No. 1 hit (with "I Think I Love You") and is no doubt a key part of her legacy, Shirley has admitted it had a negative affect on her film roles.

"The problem with Partridge — though it was great for me and gave me an opportunity to stay home and raise my kids — when my agents came to me and presented it to me, they said if you do a series and it becomes a hit show, you will be that character for the rest of your life and your film career will go into the toilet, which is what happened," she told The Vancouver Sun in 2009. "But I have no regrets."

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