Long a business reporter at the Globe and Mail, she subsequently wrote a column for the National Post before moving to her current job at the Toronto Star. She first came to national prominence in 1989 for uncovering the Patti Starr Affair, where a community leader was found to have used charitable funds for the purpose of making illegal donations to lobby the government. McQuaig was awarded the National Newspaper Award for her work on this story. The National Post has called her "Canada's Michael Moore".
She is currently best known for her series of books challenging Canada's departure from the principles of universal social programs toward an American model of strict means-based programs. She came to prominence with her best-selling 1993 book The Wealthy Banker's Wife, which challenged the argument that universal social programs such as the child welfare benefit (which had recently been discontinued) could be less expensive if funds were not paid to well-off people (such as the wife in the title). McQuaig noted that in Western Europe, such programs were common and even the Queen of the Netherlands received the benefit when she had young children.
This theme was explored further in her 1995 book Shooting the Hippo, which argued that, contrary to what was being propagated by the Liberal government (and the outgoing Conservatives) and the Bank of Canada, the country's large deficit was not caused by the so-called "enormous costs of social programs." The book details in full the government's plan to slash all social spending and to drastically increase interest rates in order to eliminate the national debt and to curb inflation. McQuaig countered these claims by arguing that two thirds of Canada's debt had actually been created by these same high interest rates; the high rate of interest on Canada's initial loan, and that social spending had little, if anything, to do with increasing the debt burden. Shooting the Hippo also explains how high interest rates benefit the wealthy (by increasing the value of large assets) but impoverish the lower-income bracket by making all types of loans (student, car, mortgages etc.) far more difficult to pay off, in effect decreasing inflation (hence keeping the value of assets intact) but increasing unemployment and creating recessions simultaneously. As small businesses deal with paying off the high interest rates on their business loans, they found it hard to cover the overhead, in effect having to lay off employees they could no longer afford to pay.
In her 1998 book, The Cult of Impotence, McQuaig challenged assumptions about the effect of globalization on industrial economies and the argument that market forces could not be controlled by government intervention. She argued that attempts to rein in inflation because of the largely theoretical benefits to economic growth from zero inflation were actually causing high unemployment and that a move towards moderate inflation and high employment would naturally raise government revenues and reduce government welfare spending.
In All You Can Eat, McQuaig challenged the system of regressive taxation that led to the unequaled accumulation of wealth by the top 1% of the Canadian population since the early 1980s. Her proposition was that by cutting taxes and government benefits, the wealthy had benefited primarily at the cost of the less advantaged, including the middle class, whose real wages and wealth had barely grown during that period of time.
Her 2004 book It's The Crude, Dude: War, Big Oil and the Fight for the Planet is an investigation of United States foreign policy from the assumption that it acts in order to secure its supply of petroleum products, particularly in light of the recent actions of the United States in Iraq.
In her latest book Holding the Bully's Coat: Canada and the US Empire (2007), McQuaig argues that Canada should reject the role of adjunct to the United States and find its own way in the world.
In a July 29, 2008, article in the Toronto Star, McQuaig writes that "Obama is resolutely in sync with the existing script prepared by Washington power brokers, not even veering far from the Bush White House."
She is a graduate of the University of Toronto and Branksome Hall.
In the CBC TV comedy The Newsroom, she played herself as a guest to discuss her book Shooting the Hippo. This led to this exchange:
Ken Finley (News Director, played by Ken Finkelman): "(Shooting the Hippo I loved that book)...what does it mean?"
McQuaig: "I actually explained that in the opening line of the book."
Followed by another:
Jim Walcott (Anchor, played by Peter Kelegan): "I really liked the title of your book "Shooting the Hippo", but don't you think you would've sold more copies if you had a picture of a dead hippo on the cover?"
By the end of the show, she storms off in a huff when she finds out that the producers of the show have asked conservative commentator Hugh Segal to appear for "balance".
She was famously criticized by Conrad Black who once commented that she deserved to be "horsewhipped". He later hired her as a columnist when he owned the National Post.