2017 World Junior Ice Hockey Championships

The 2017 World Junior Ice Hockey Championships was the 41st edition of the Ice Hockey World Junior Championship (WJC or WM20). The main tournament was co-hosted by the Bell Centre in Montreal, Quebec and Air Canada Centre in Toronto, Ontario. This was the 14th championship that Canada had hosted. Montreal and Toronto also jointly hosted the 2015 edition. The tournament consisted of 30 games between 10 nations.

Group A preliminary games, as well as the medal rounds, were hosted by the Bell Centre in Montreal. The Air Canada Centre in Toronto hosted preliminaries in Group B, including the host country of Canada. The tournament also initiated several year-long celebrations, the 375th anniversary of Montreal's founding; the 100th anniversary of the National Hockey League's founding in Montreal; the 100th anniversary of Hockey Canada's origins; the 50th anniversary of Montreal's Expo 67; the 150th anniversary of Canadian confederation; and the 100th anniversary of the Toronto Maple Leafs. The Maple Leafs had planned to make the WJHC the centrepiece of their 100th-anniversary celebrations.

The event was organized by Hockey Canada, Hockey Québec, Ontario Hockey Federation, Montreal Canadiens, Maple Leaf Sports & Entertainment and Evenko. Montreal and Quebec provided C$1 million and C$2 million in funding, respectively, for both the 2015 and 2017 editions.

For the first time in the history of the event, the defending champion (Finland) had to compete in the relegation round. Latvia was relegated to Division I-A for 2018 by merit of their tenth-place finish.

Player eligibility
A player was eligible to play in the 2017 World Junior Ice Hockey Championships if:
 * the player was of male gender;
 * the player was born at the earliest in 1997, and at the latest, in 2002;
 * the player was a citizen in the country he represented;
 * the player was under the jurisdiction of a national association that was a member of the IIHF.

If a player who has never played in IIHF-organized competition wishes to switch national eligibility, he must have played in competitions for two consecutive years in the new country without playing in another country, as well as show his move to the new country's national association with an international transfer card. In case the player has previously played in IIHF-organized competition but wishes to switch national eligibility, he must have played in competitions for four consecutive years in the new country without playing in another country, he must show his move to the new country's national association with an international transfer card, as well as be a citizen of the new country. A player may only switch national eligibility once.

Match officials
The International Ice Hockey Federation selected 12 referees and 10 linesmen to officiate during the tournament:

Referees
 * 🇸🇪 Tobias Björk
 * 🇨🇦 Darcy Burchell
 * 🇨🇿 Jan Hribik
 * 🇸🇰 Jozef Kubus
 * 🇺🇸 Mark Lemelin
 * 🇸🇪 Marcus Linde
 * 🇩🇪 Marian Rohatsch
 * 🇫🇮 Anssi Salonen
 * 🇺🇸 Brett Sheva
 * 🇧🇾 Maxim Sidorenko
 * 🇨🇿 Robin Šír
 * Daniel Stricker

Linesmen
 * 🇸🇪 Jimmy Dahmen
 * 🇺🇸 Jake Davis
 * Nicolas Fluri
 * 🇧🇾 Dmitry Golyak
 * Henrik Haurum
 * 🇩🇪 Lukas Kohlmuller
 * 🇷🇺 Yakov Paley
 * 🇨🇿 Libor Suchanek
 * 🇫🇮 Sakari Suominen
 * 🇨🇦 Nathan Vanoosten

Format
The four best ranked teams from each group of the preliminary round advanced to the quarterfinals, while the last-placed team from both groups played a relegation round in a best-of-three format to determine the relegated team.

Preliminary round
''All times are local. (Eastern Standard Time – UTC−5)''

Relegation round
Note: was relegated to the 2018 Division I A

Goaltending leaders
(minimum 40% team's total ice time)

Tournament awards
Reference: Most Valuable Player
 * Defenceman: 🇨🇦 Thomas Chabot

All-star team
 * Goaltender: 🇷🇺 Ilya Samsonov
 * Defencemen: 🇨🇦 Thomas Chabot, 🇺🇸 Charlie McAvoy
 * Forwards: 🇷🇺 Kirill Kaprizov, 🇸🇪 Alexander Nylander, 🇺🇸 Clayton Keller

IIHF best player awards
 * Goaltender: 🇸🇪 Felix Sandström
 * Defenceman: 🇨🇦 Thomas Chabot
 * Forward: 🇷🇺 Kirill Kaprizov

Group A
The Division I A tournament was held in Bremerhaven, Germany, from December 11 to 17, 2016.

Group B
The Division I B tournament was held in Budapest, Hungary, from December 11 to 17, 2016. The hosts, entering as the bottom seed, won promotion for the second year in a row.

Group A
The Division II A tournament was held in Tallinn, Estonia, from December 11 to 17, 2016.

Group B
The Division II B tournament was held in Logroño, Spain, from January 7 to 13, 2017.

Division III
The Division III tournament was held in Dunedin, New Zealand, from January 16 to 22, 2017. Turkey defeated China in the Gold medal game to achieve promotion to Division II. Chinese Taipei returned to play for the first time since 2011, losing all but their final game.