The Ontario general election of 1987 was held on September 10, 1987, to elect members of the 34th Legislative Assembly of the Province of Ontario, Canada. The governing Ontario Liberal Party, led by David Peterson, was returned to power with their first majority government in half a century, and the second-largest majority government in the province's history. Peterson had successfully managed to govern with a minority in the Legislature by obtaining the co-operation of the Ontario New Democratic Party, led by Bob Rae. It was through the NDP's support that Peterson was able to form a government, even though the Progressive Conservative Party had won a slightly larger number of seats in the previous election.