In 2003, the SARS outbreak, coming on the heels of a long-term lack of investment in Toronto’s attractions and marketing, created a crisis for the Toronto region’s tourism industry – the 2003 Toronto Summit was the only event held at the Metro Toronto Convention Centre that June. In response, the Toronto City Summit Alliance created the Toront03 Alliance to help promote travel to Toronto. Led by Chair David Pecaut and President Kevin Shea, T03 featured what has become an Alliance hallmark: a multi-stakeholder board including leaders from business, arts and entertainment, tourism organizations, the restaurant and accommodation industry, and governments.

With a focus on American travelers, T03 supported and promoted the "Molson Canadian Rocks for Toronto Concert" featuring the Rolling Stones in July 2003 and the Conan O’Brien Show in Toronto in February 2004. Forty-two thousand American concert ticket buyers attended the Rolling Stones concert and contributed $75.2 million in additional tourism spending over the week before the concert. In addition, T03's direct response advertising drew over 100,000 American visitors to Toronto through the fall of 2003, generating roughly $70 million in visitor spending.

As these activities concluded in 2004, T03 turned its attention to rectifying some of the fundamental challenges to the tourism industry that it had identified. In particular, T03 invested, together with Tourism Toronto and the City of Toronto and provincial governments, in developing a unified and long-lasting brand development strategy for Toronto.

T03's efforts were funded by a $10 million contribution from the federal government and $1.22 million in private sector donations, including $200,000 from each of the major banks.