JLM / Splash News 1 / 27
JLM / Splash News 1 / 27

Giddy up, Harlow!

Nicole Richie and Joel Madden's little girl, Harlow, officially turned four on Jan. 11, but she celebrated her latest milestone with a "Toy Story"-themed bash in Studio City, Calif., on Monday.

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Held at The COOP playspace, little Harlow's party was attended by 35 kids, and all were treated to a visit from the Pixar film's characters Woody, Jessie and Buzz.

Along with their children, Gavin Rossdale, Tobey Maguire's wife Jen Meyer, Sara Gilbert and Rachel Zoe also helped fete Harlow on her special day.

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"Harlow started crying when everyone sang happy birthday and Joel said she was crying tears of joy," an onlooker told Us Weekly of the 4-year-old, who munched on pizza and juice, along with a sugar-free Cake Diva confection, at the bash.

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"Everyone had a blast and Joel and Nicole said it was their best kids party yet," the insider explains of Madden, 32, and Richie, 30, also the parents of Sparrow, 2.

"Toy Story" is clearly a big hit with the Richie-Maddens. In 2010, Richie dressed up as cowgirl Jessie for Halloween.