The Toronto Symphony Orchestra (TSO) was a Canadian orchestra based in Toronto, Ontario that was active during the first two decades of the 20th century under the leadership of conductor and pianist Frank Welsman. It was the first professional orchestra that existed for any notable length in the city of Toronto. After 13 seasons of performance, the orchestra folded in 1918 because of problems related to World War I.[1][2] The current Toronto Symphony Orchestra is unrelated to this one.