"We have agreed to a trial separation that dates back for some time," the pair said in a statement released Monday. "The reason for this separation is to better understand ourselves and the qualities we need in a partner and for our marriage." TMZ first reported the news.
Arquette, 39, and Cox, 46, wed in 1999 after meeting on the set of the first Scream film. The actors co-star in the fourth installment of the Wes Craven-directed horror franchise, set to be released in April 2011.
"We remain best friends and responsible parents to our daughter and we still love each other deeply," the statement said. "As we go through this process we are determined to use kindness and understanding to get through this together."
The couple has one daughter together, Coco Riley, 6.
Reps for the Cougar Town actress did not immediately respond to TVGuide.com's request for comment.