The Ontario Youth Parliament (OYP), formerly the Ontario Older Boys' Parliament, is one of a number of provincial youth model parliaments across Canada. Each year, the organization holds a four-day debate conference on Family Day weekend for youth ages 14 to 21 from Ontario, Canada. The organization has roots within the United Church of Canada dating back to 1907. The first session of the Older Boys' Parliament met in the Ontario Legislative Building at Queen's Park in Toronto in January 1925. As a result, the OYP, as successor to the Older Boys' Parliament, is one of the oldest youth parliaments in Canada. Gordon Lapp of Brighton served as the first Premier.

In 1969, the Older Boys' Parliament was succeeded by the OYP and is now a non-denominational Christian-based organization that is open to participants of all faiths. It combines components of parliament-style debate, social and leadership development activities and exploration of spirituality. The debate is modeled after the Legislative Assembly of Ontario, with mock legislation written by members of the youth cabinet on current issues facing youth in Canada. Social activities include two dances and a formal banquet, secret friends, and team-building games. The spiritual side of OYP is addressed through open nightly discussion on the theme chosen for that year and attendance at the host church's worship service.