The split is "amicable" and they won't find it awkward or uncomfortable to socialize together, thier e-mail said.
"Dear friends, we wanted to let you know that we have decided to embark upon this next phase of our lives by living separately," the e-mail said. "This has been a difficult decision, but we both believe it is the right thing to do. Our parting is amicable, and we will remain friends and continue to be active in our community, sometimes together, sometimes separately."
The couple asked for friends to "respect our privacy, and our decision, and wish us well."
The e-mail was signed "Ed and Midge," with this postscript:
"Please do not hesitate to include both of us in social occasions as we will not find it awkward or uncomfortable."
A source familiar with details of the separation said the couple are not planning to divorce and will likely be seen in public together.
Midge, 64, is expected to remain in the couple's East Falls home while the former governor, 67, lives elsewhere.
The couple, who married in 1971, has one son, Jesse, who practices law in Philadelphia.
They plan to share custody of their two golden retrievers, Ginger and Maggie.
Although the e-mail doesn't cite a reason for the split, Rendell has long been the subject of speculation involving younger women, typically leggy blondes.
He most recently turned heads in May when he arrived at an Election Day lunch at the Famous 4th Street Deli with Kirstin Snow, a state employee and former Miss Pennsylvania.
Gov. Corbett's media office yesterday said that Snow's job as director of commonwealth media services ended on Jan. 18, the day Rendell left office.
A source said Snow remains in Harrisburg but is helping the former governor with several projects. Rendell signed a deal two weeks ago to serve as an "NBC News" political analyst.
Snow declined to comment yesterday about Rendell's split.
A Daily News story about Rendell and Snow lingering over their Election Day lunch after other pols had departed prompted Philadelphia magazine in July to explore rumors of an affair.
Rendell and Snow denied the rumor in the story, which ran with a portrait of a grinning Rendell seated as Snow stood smiling and standing behind him, resting her arms on his shoulders.
As Rendell's second term as governor was winding down, he and Snow were often spotted around Harrisburg having dinner, attending her son's soccer games and enjoying the Susquehanna River on her pontoon boat.
Rendell angrily denounced the media after the magazine story broke in July.
"No comment," Rendell fumed when a reporter from the Roxbury News website asked about the story in the state Capitol. "It's personal. It's between me and my family. There's no governmental interest here. What I said and what Dr. Snow said in Philadelphia magazine is the truth. That's it. Don't ask me again."
Snow had told the magazine that she was surprised it took so long for rumors to circulate about her relationship with the governor, adding that she worried about gossip hurting his wife.
Snow, who earned a doctorate in business administration through a distance-learning program from Southwest University, in Kenner, La., was Miss Pennsylvania in 1994, Mrs. Pennsylvania in 2005 and Mrs. American Dream in 2007.
Twice divorced, she has also appeared in an infomercial for DivorceDoneRight.com.
Snow is not the first woman to spark speculation in newspaper and magazine articles about Rendell.
During his time as mayor he was often seen around Philadelphia with lobbyist Holly Kinser while she was married to former House Speaker Bill DeWeese.
As governor, Rendell also was noticed to be very friendly with Leslie McCombs, a former Pittsburgh television anchor who went into lobbying.
Kevin Feeley, a public-relations executive who served in Rendell's mayoral administration, confirmed the existence of the e-mail from Rendell and his wife. Feeley said they would have no further comment on the separation.
The couple has a tight circle of close friends, many from their college and law school days. Many of those friends declined to comment yesterday.
Comcast Executive David L. Cohen, who served as Rendell's chief of staff when he was mayor, repeated the couple's call for privacy.
"Although Ed and Midge are a public couple, this is a private matter and a personal matter, and I hope everyone will respect their privacy," Cohen said.
H.G. "Buzz" Bissinger, who chronicled Rendell's first term as mayor in his book "A Prayer for the City," said the news of the split didn't come as a surprise.
"My sense of Midge and Ed was, when they were with each other they were very loving and a couple," said Bissinger. "The rumors of Ed being with other women are as old as Adam and Eve. And I don't think they were rumors."
Bissinger said he thought that the pledge by the Rendells to remain friends was likely true.
"I think they really were affectionate and comfortable," Bissinger said. "Marriages end and people get separated. I think they will remain friends because that's what they always were."
Proof that the couple plan to socialize together could be found at the Palestra Saturday night as they, joined by their son and his wife, watched the University of Pennsylvania men's basketball team take on Harvard.
Midge Rendell and her daughter-in-law were flying yesterday to Australia for a wedding.
Midge and Ed, who would celebrate their 40th wedding anniversary on July 10, met in 1968, when she was a junior at the University of Pennsylvania and he was a third-year student at Villanova law school. A mutual friend - now Phillies President Dave Montgomery - took Midge to a party at Rendell's apartment, also known as the "ape house."
The blond, blue-eyed Marjorie "Midge" Osterlund caught Rendell's eye. The next day he called Montgomery to see if he could date Midge.
"He was very high energy in the way he talked and the things he talked about," Midge Rendell said in a 2003 interview with the Daily News. "He played mind games, like if you were on a desert island what three things would you take with you. We had a lot of fun."
They dated until her graduation, when she called it off to see what else was out there.
But they renewed the romance in Washington, D.C., where she was studying at Georgetown Law School and Rendell, then an assistant district attorney in Philadelphia, went to campus to interview potential recruits.
They had dinner and when she took him to the train station in Washington, she proposed.
"He'd proposed to me before, so it wasn't like it came out of nowhere," she told the Daily News in 2003. "But I just asked him. . . . I don't think I did plan it."
In July 1971 they married at the plush DuPont Country Club, in Delaware. Midge transferred to Villanova, where she finished her law degree.
Midge Rendell became a U.S. district judge in 1994. She was appointed by President Bill Clinton, and Sen. Arlen Specter helped steer her nomination through the U.S. Senate. Both were close allies of her husband's. In 1997, she was elevated to the U.S. Third Circuit Court of Appeals.