John Aiken MacLaren bought the Toronto office of Campbell-Ewald in 1935, renaming it MacLaren Advertising. The agency soon established itself as a leader in Canadian advertising, being the first agency to have a radio department, research department, direct mail and sales promotion department, as well as a poster and store display division. As the business grew, the agency established branches in Montreal, Quebec and London.
In 1942, MacLaren acquired the Norris-Patterson agency, which was absorbed into MacLaren's business structure.
By 1954, MacLaren was Toronto's largest advertising agency and one of the top 50 companies in North America. Branch offices opened in Vancouver, Winnipeg and Ottawa soon after.
Because of its early success in radio broadcast production, MacLaren was poised to be a major force in the early development of TV in Canada. By 1955, the agency and its clients dominated the medium, with agency staff writing and producing some 85% of network programming. By 1960, MacLaren was Canada's No. 1 agency.
After Mr. MacLaren's death in 1955, leadership of the agency passed to Einar Rechnitzer, a longtime employee who had headed the GM business. When Mr. Rechnitzer retired in 1964, George Sinclair succeeded him. Under his management, the agency established offices beyond Canada, acquiring agencies in London and Paris, as well as opening an office in Nassau. MacLaren was also expanding at home, opening an office in Quebec City and a public relations subsidiary, Carlton Cowan, in Toronto. In 1979, MacLaren opened a creative boutique, the Gloucester Group, which was later folded into the parent company.
MacLaren was closely tied to the Liberal Party of Canada until the Liberals lost power in 1979, causing massive layoffs and a complete restructuring of the agency.
Under Creative Director Bill Durnan, the agency introduced a hard rock-and-roll campaign in 1982 for Molson called "Dancin' in the Streets." Its ads for Molson included the 1985 "What beer's all about" effort and the 1992 "I Am Canadian" campaign, which flaunted Canadian national pride. The account went into review, however, and the agency lost the business in 1999.
In 1984 for Unilever's Sunlight detergent, the agency introduced a lifestyle campaign that recognized that for some people, the whiteness of their laundry was not the most important issue in their life. "It's part of the family" and "We know you have better things to do" were key themes that drove the Sunlight business in the 1980s.
In 1988, MacLaren was sold to Lintas Worldwide and renamed MacLaren:Lintas. In 1990, the agency won the Buick and Pontiac accounts. In response to new ideas in client service, the agency became the first in Canada to separate its media department into an independent unit.
The No. 4 agency in Canada at the turn of the 21st century, it had offices in Toronto, Vancouver and Calgary and a French-language agency, Marketel, in Montreal.
In 2001, MacLaren McCann Canada was the No. 2 agency in Canada, with gross income of $83.2 million, down 7.3% over 2000, on billings of $603.9 million.