.gif) Ontario Series Lacrosse | |
| Sport | Box lacrosse |
|---|---|
| Founded | 1999 |
| No. of teams | 6 |
| Country | Canada |
| Most recent champion(s) | Six Nations Rivermen (2019) |
| Most titles | 7 (Owen Sound Woodsmen) |
| Official website | Ontario Senior Lacrosse |
Ontario Series Lacrosse, known as the OLA Senior B Lacrosse League from 1999-2019, is a Senior box lacrosse league based out of Ontario, Canada sanctioned by the Ontario Lacrosse Association. Many of the players in the league play or have played in the National Lacrosse League. OSL winners earn a chance at the national championship—the Presidents Cup.