Young People's Theatre

Rubeš created the Museum Children's Theatre in her Toronto kitchen and opened Alice in Wonderland at the Royal Ontario Museum in 1963. Rubeš staged her first YPT show, The Looking Glass Revue, at the Colonnade Theatre in 1966.

Before being located at its current site, YPT staged shows at the St. Lawrence Centre, the Ontario Science Centre and Toronto's Firehall Theatre. The company also toured to schools throughout Ontario, and toured the play Inook and the Sun in the United Kingdom. In 1977, YPT staged its first show in its current location with an adaptation of The Lost Fairy Tale. YPT added a drama school in 1969. The Drama School operates in Downtown Toronto and Etobicoke.

Several stage and screen actors have appeared on the YPT mainstage since the 1970s, including Martin Short, Megan Follows, Brent Carver, Cynthia Dale, Fiona Reid, Gordon Pinsent, R.H Thomson, Sheila McCarthy and Eric Peterson. Celebrities such as Drake and Kiefer Sutherland also attended YPT's Drama School.

In the spring of 2001, the theatre was renamed Lorraine Kimsa Theatre for Young People after a donation of $1.5 million from Kevin Kimsa in honour of his mother, Lorraine. In March 2011, the theatre announced a change back to its original name.

The Slaight family's 2015 donation of $3 million resulted in the creation of the Ada Slaight Education Centre at YPT. At the time it was the largest non-capital gift received by a Toronto theatre company. In 2022 a gift from the Slaight Family resulted in the renaming of the company's Mainstage to the Ada Slaight Stage. In 2016 YPT was one of a number of theatres offering free tickets to newly arrived Syrian refugees.

In 2020, YPT began a $13.5 million expansion project that resulted in the purchase of a multi-use building - YPT 161 Studios - across the street from the theatre on Front Street. The theatre also underwent extensive renovations that were unveiled in Sept. 2022.