Penelope's 1st birthday party was a soaring success! Kourtney Kardashian and boyfriend Scott Disick's little girl turned 12 months old on July 9, and the couple celebrated over the weekend with a blowout party on Sunday, July 14.

An insider tells Us Weekly that Kris Jenner hosted approximately 150 family and friends at her L.A. home in honor of her granddaughter's special day. Also in attendance at the party planned by Sharon Sachs was Penelope's baby cousin, North West, who is currently living in Jenner's home with mom Kim Kardashian and dad Kanye West. But a source tells Us that the one-month-old newborn "stayed in the house because she's too little to be around that many people. She's doing great though!"

PHOTOS: Penelope's baby album

Kourtney, 34, decorated her mom's house with giant balloons from Geronimo Balloons. "Balloon partyyyyy!" she tweeted Sunday with photos of a decor. "Major balloon party, that is!" In the pictures, Kourtney, wearing a short floral dress and big sunglasses, poses between huge pink and white balloons outside in the yard.

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A source tells Us that Geronimo Balloons designed "3 ft. balloons with handmade paper frill to match the party colors -- light pinks, nude pink, rose and creams. Each balloon takes the equivalent helium of 30 regular size balloons. Prices for similar designs to the Kardashians' is $150 each."

The insider also tells Us that Kourtney selected the colors and had three balloons "greeting party guests at the entrance and in the garden."

PHOTOS: Kourtney and Scott's adorable son Mason

On her daughter's July 9 birthday, the Keeping Up With the Kardashians star, who is also mom to son Mason, 3, tweeted, "Happy 1st birthday to my sweet precious angel. I can not believe it has been a year. Truly blessed."

This article originally appeared on Kourtney Kardashian Throws Daughter Penelope a 1st Birthday Party