Inside Ashlee Simpson and Evan Ross's Extravagant Engagement Party

Older sister Jessica Simpson looked svelte in a low-cut mini-dress.

ByABC News
March 27, 2014, 2:47 PM
Jessica Simpson posted this image on Instagram with this caption: "Celebrating my best friend and sister @missbananahammock @ashleesimpsonofficial. I love her so much!, " March 26, 2014.
Jessica Simpson posted this image on Instagram with this caption: "Celebrating my best friend and sister @missbananahammock @ashleesimpsonofficial. I love her so much!, " March 26, 2014.
jessicasimpson/Instagram

March 27, 2014 -- What a celebration!

Ashlee Simpson and Evan Ross celebrated their engagement with a big party -- and older sister Jessica couldn't help but gush about the event.

"Celebrating my best friend and sister @missbananahammock @ashleesimpsonofficial," she wrote on Instagram. "I love her so much!"

Meet Ashlee Simpson's Fiancé Evan Ross

Ashlee Simpson, 29, and Ross, 25, announced their engagement earlier this year. Now, they're making time to celebrate with people they love.

"What an amazing engagement party with all of our loved ones! We gettin' married :)" Simpson tweeted, along with a photo from the lavish event.