Dennis Quaid's Wife Files for Divorce ... Again

Dennis Quaid and his wife are heading for divorce for the second time ... TMZ has learned.

Kimberly Quaid filed the divorce petition Tuesday in L.A. according to Dennis, who was working in Vancouver on his show Crackle's "The Art of More" at the time, but it's clear this was NOT a blindside. In a joint statement, Dennis and Kimberly tell TMZ ... "After careful consideration, we have decided to end our 12 year marriage. The decision was made amicably and with mutual respect toward one another."

Kimberly first called things off back in March of 2012 ... only to change her mind a couple months later and withdraw the divorce filing.

Dennis and Kimberly have been married since 2004. They made it through tragedy when their twins were born in 2007 at Cedars Sinai, and staffers mistakenly gave the infants a near fatal dose of Heparin.

Sources connected to the couple tell us much of the split has been sorted out already -- including the divvying up of assets -- and they plan to share custody of their now 8 year-old kids, Thomas and Zoe.