A native of Canada, Mr. Breen is joining MacLaren McCann, Toronto, part of McCann-Erickson WorldGroup, which is owned by Interpublic Group of Cos. His last day at Y&R, Chicago, is today.
At MacLaren McCann, Mr. Breen becomes chairman-CEO, duties previously handled by Tony Miller, a vice chairman of McCann-Erickson WorldGroup who took the helm of the agency on an interim basis one year ago.
"Howard is a terrific hire," said Mr. Miller, who now returns to the vice chairmanship full time.
MacLaren McCann's clients include automaker General Motors Corp. and Canadian media company Rogers Communications; it employs 740 people working in 11 separate divisions.
A spokeswoman for Y&R Advertising said a replacement to Mr. Breen will not be named. The heads of the Chicago, Toronto and San Francisco offices who formerly reported to Mr. Breen will now report directly to Michael Dolan, chairman-CEO of Y&R Advertising and its parent, Young & Rubicam.