He positioned himself in contrast to what he termed "the politics of division," which he maintained is practised by Prime Minister Stephen Harper, NDP Leader Tom Mulcair and Parti Quebecois Premier Pauline Marois.
"My friends, I have no interest in joining Mr. Harper and Mr. Mulcair in a competition to see who can make Canadians angrier," he told some 3,000 delegates.
"We are here to hope. We are here to work hard. We are here to build. We are here to put together the team and the plan to make this country better."
That said, Trudeau was not above taking shots at his rivals, particularly Harper whom he indirectly blamed for the popularity of the PQ's controversial charter of Quebec values, which bans public servants from wearing prominent religious symbols.
Under Harper, Trudeau said incomes of middle class Canadians have stagnated, household debt has skyrocketed and the gap between rich and poor has widened. And that, he said, has created an environment in which intolerance thrives.
"People are susceptible to fearful, divisive messages when they're worried, worried about their jobs, their debts, their retirement, their kids' futures," he said.
"In a growing and fair economy, the PQ's divisive plan would not only be unrealistic, it would be unthinkable."
As he's done since launching his leadership campaign 18 months ago, Trudeau stressed that his focus is on improving the lot of the struggling middle class. And he urged the delegates to keep tightly focused on that goal as they consider policy resolutions over the next three days.
The occasion was marred slightly when a rehearsal of his opening speech was inadvertently broadcast to the media room several hours before he was to officially welcome some the delegates to his hometown of Montreal.
The practice run included a video call to his wife, Sophie Gregoire, who is staying at home in Ottawa because she's due to give birth to their third child any day, and their two children.
When it came time for the real thing, seven-year-old Xavier stole the show, jumping on and off the couch where his mother was attempting to address the convention and shoving his face into the camera.
Gregoire used the call to tell Trudeau she's proud of him and to remind him to be "courageous, fearless, humble and to remember that, no matter how much power or influence or responsibility we are given ... we are here to serve all Canadians."
Trudeau also took aim at the Harper government's proposed overhaul of the Elections Act, saying it can be summed up as: "The government will let you vote, if you insist, but really they'd rather you didn't."
Canadians are counting on Liberals to fight the reforms, he said, vowing: "We won't let you down."
It was at that point during the rehearsal that Trudeau demonstrated his mastery of television, instructing camera operators on the shot he wanted so that's he'd appear to be directly addressing viewers.
"That's a moment when the camera needs to be locked on me because I stare right at the camera," he advised.
Trudeau repeatedly told delegates that the convention is about building "the team and the plan" that will take the party into the 2015 election.
The convention is being used to showcase some of the star candidates Trudeau has recruited to run for the party in the next election and to give a glimpse of the platform he intends to run on.
The emphasis on team and plan is reminiscent of the campaign run by Jean Chretien in 1993, when he led the Liberals out of opposition wilderness with the refrain: "We have the plan. We have the people. We can make a difference."
It is aimed at dispelling Canadians' qualms — stoked by Conservative attack ads — that Trudeau has neither the judgment nor experience to be prime minister.
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