Born in Lebanon, Mac Harb graduated from the University of Ottawa with a Bachelor of Science and an M.A. in Engineering. A former engineer for Northern Telecom and professor at Algonquin College in Ottawa, Mr. Harb's political career started at the municipal level in Ottawa in 1985 as an alderman, and then as Deputy Mayor from 1987 to 1988.

In 1988, Mr. Harb was elected to the House of Commons as a Member of Parliament for Ottawa Centre. Former Opposition Critic for Public Works, Urban Affairs and Housing, Mr. Harb sat on such committees as the Standing Committee on Multiculturalism and Citizenship, House Affairs, Public Accounts, and the Members Services Board. He also co-chaired the Liberal Task Force on Infrastructure in 1990.

Mr. Harb was Parliamentary Secretary to the Minister of International Trade from December 1993 until 1995.