Smith outdid Wayne Gretzky in his final season of junior hockey with Ottawa, winning the Ontario Hockey Association scoring title in 1977-78 with 192 points (69 goals, 123 assists), 10 more than Gretzky. The Minnesota North Stars selected Smith with the No. 1 pick of the 1978 NHL Draft.
The 6-foot-4 center from North Sidney, Nova Scotia, won the Calder Trophy as the NHL's top rookie in 1978-79, scoring 30 goals and finishing with 74 points. Two years later, he finished with 93 points, including 64 assists, helping the North Stars advance to the Stanley Cup Final for the first time. Smith finished with 25 points (eight goals, 17 assists) in 19 Stanley Cup Playoff games, although the North Stars lost the Final to the New York Islanders in five games.