The Weeds star, 44, says she remembers wishing her parents would adopt a sibling for her when she was growing up.
"I still think it's something everyone should do if they can and want to," Parker said Saturday night during a Q&A with New Yorker journalist John Colapinto.
"Especially after having been to a Third World country and having seen the desperation there and the need and all the children and holding those children and seeing them and touching them," she said.
Of her own experience, "I can’t adopt 500 children," she said, "but I did adopt this one beautiful little girl, and it was an amazing thing."
A Late NightParker arrived at the 10 p.m. event after filming a message for Worldwide Orphans, the organization that helped find her daughter. She told the audience she broke her usually strict bedtime rule and took Ash, who is now 2, along for the shoot.
"I'm very scheduled, so she was asleep," said Parker. "I had to quietly wake her up, which I never wake up my children, but [I told her] it was for the other orphans of the world."
The New York City-based actress says she's lost the yen for nightlife since becoming single mommy to Ash and son William, 4 (and whose dad is actor Billy Crudup).
"I get a lot of invitations to go to a lot of things, and I don't go to lots of things because I want to put my kids to sleep at night," she said.
And what does William think of her work on her hit show Weeds, where she stars as a marijuana-dealing mom?
"He thinks I'm on a show about plants," she says with a laugh.
For more from Mary-Louise, check out PEOPLE's Celebrity Baby Blog.