Katherine Heigl and husband Josh Kelley shared an adorable picture of their 16-month-old daughter, Adalaide, all grown-up via Instagram on Monday, Aug. 12 Credit: Courtesy of Josh Kelley

Katherine Heigl's second adopted daughter, Adalaide Marie Hope Kelley, is all grown up! The former Grey's Anatomy actress and musician husband Josh Kelley revealed a picture of their youngest via Instagram on Monday, Aug. 12.

"Momma bear @katiemheigl hangin outside with Adalaide during another beautiful afternoon up here in the mountains," the 33-year-old singer wrote.

Dressed in cowboy boots with a matching hat, Heigl showed off a smiling Adalaide wearing a sundress while sucking on her thumb. A beaming Heigl held her hand while holding a drink in the other.

Adalaide was born in Louisiana and joined big sister Naleigh, 3 -- whom they adopted from South Korea -- in April 2012.

"She is loving being a big sister!" a source told Us Weekly of Naleigh in May 2012. "Everyone is doing great. They're thrilled to add to the family!"