Nicole Richie and Joel Madden Are Engaged

Nicole Richie and Joel Madden are engaged to be married, the couple confirmed Monday.

Richie shared the news during a taping of the "Late Show" with David Letterman, and Madden, lead singer for the band Good Charlotte, confirmed the announcement on his Twitter page.

Photos: Who Else Is Getting Married?

"Yep. i'm engaged. Very happy. Yeah we've been engaged for a while so your all kind of late on that. But Thanks for the hooplah all the same," he wrote Monday night.

He also thanked friends and family for not leaking the news, saying, "Thats why i love my family and friends. None of them are sources. All good tight lipped people who let us enjoy it! Thanks everybody."

Richie and Madden began dating in December 2006, and have two children together - daughter Harlow, 2, and son Sparrow, 5 months.