Major League Soccer's regular season runs from March to October. Teams are divided into the Eastern and Western Conferences, playing 34 games in an unbalanced schedule. For 2018, with 23 teams, each team plays 23 games against teams in its conference and 11 games against teams from the opposite conference. For 2019, with 24 teams, the anticipated schedule would be that each team would play each of the teams within its conference twice, for 22 matches, and each of the teams from the other conference once, for 12 additional matches, and 34 total matches. Midway through the season, teams break for the annual All-Star Game, a friendly game between the league's finest players and a major club from a different league. At the end of the regular season, the team with the highest point total is awarded the Supporters' Shield.
Unlike some soccer leagues around the world, but similar to other leagues in the Americas, the MLS regular season is followed by the 12-team MLS Cup Playoffs in November, ending with the MLS Cup championship final in early December.
Although some commentators have argued that playoffs reduce the importance of the regular season, Commissioner Don Garber has explained "Our purpose is to have a valuable competition, and that includes having playoffs that are more meaningful."
Major League Soccer's spring-to-fall schedule results in scheduling conflicts with the and with summertime international tournaments such as the World Cup and the Gold Cup, causing several players to miss some MLS matches.
While MLS has looked into changing to a fall-to-spring format, there are no current plans to do so. If the league were to change its schedule, a substantial winter break would still be necessary due to teams being located in harsh winter climates. It would also have to compete with the popularity and media presence of the (NFL) in the fall and winter as well as the National Basketball Association (NBA) and National Hockey League (NHL), which both run on fall-to-spring schedules.
MLS teams also play in other international and domestic competitions. Every year, five MLS teams — four from the U.S. and one from Canada — play in the CONCACAF Champions League against other clubs from the CONCACAF region (Mexico, Central America, and the Caribbean). Two U.S.-based MLS teams qualify based on MLS regular-season results: the winner of the Western conference and the winner of the Eastern conference. The third U.S. team to qualify is the winner of the MLS Cup. A fourth U.S.-based MLS team can qualify via the U.S. Open Cup, where U.S.-based teams compete against lower division U.S. clubs. If a team qualifies through multiple berths, or if any of the MLS berths are taken by a Canada-based MLS team, the berth is reallocated to the best U.S.-based team in the Supporters' Shield table that has otherwise failed to qualify. Canadian MLS clubs play against lower division Canadian clubs in the Canadian Championship for the one Champions League spot allocated to Canada. No MLS club has won the Champions League since it began its current format in 2008, with Mexican clubs dominating the competition, but MLS teams have reached the final three times: Real Salt Lake in 2011, Montreal Impact in 2015, and Toronto FC in 2018. Beginning in 2018, the previous year's MLS Cup champion will play in the Campeones Cup, a single game against the Campeón de Campeones from Liga MX, hosted by the MLS team in September. The first edition will see Toronto FC take on Tigres UANL.