Their rep told PEOPLE that Grace Avery Costner arrived at 5:46 p.m. California time. She weighed 7 lbs., 11 oz., and was 21 inches at birth.
Grace will have plenty of older, wiser siblings to ask for advice! Her siblings are: Hayes Logan, 16 months, Cayden Wyatt, 3, Liam, 13, Joe, 22, Lily, 23, and Annie, 25.
Kevin and Christine have been married since 2004.