The league was divided into two divisions with the East Division having seven teams and the West division having eight teams. Each team played 12 games against teams in their own divisions (East played each opponent home and away, while West played five of the teams twice, and the remaining two teams once). The top two teams from each division advanced to the playoff semi-finals, with the winner of the championship final in November qualifying for the
2022 Canadian Championship. Because the season began three months later than normal and with very short notice, some clubs have opted to delay their return to Premier Division competition until the 2022 season. As a large portion of the L1O player pool consisted of university and college student athletes, some sides would have limited squads after Labour Day. To combat these challenges, the league created a short-season ‘Summer Championship Series’ for 2021, which will conclude by Labour Day. In addition, the Reserve Division will return, following a similar format to the Premier Division, featuring 21 teams in three division playing 12 matches, with the top teams advancing to the playoffs and featuring Championship Finals weekend on November 6-7. ==Clubs==