What Is 33rd Legislative Assembly of Ontario

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Last updated: April 15, 2026

Quick Answer: The 33rd Legislative Assembly of Ontario convened from November 15, 1985, to May 1, 1987, following the 1985 provincial election. It was a minority legislature led by the Liberal Party under David Peterson after the Progressive Conservatives lost power after 42 years.

Key Facts

The 33rd Legislative Assembly began on November 15, 1985, and ended on May 1, 1987.
David Peterson (Liberal) became Premier after a Liberal-NDP accord ended 42 years of Progressive Conservative rule.
The Progressive Conservatives, led by Frank Miller, won the most seats but lost power due to a minority government.
The Assembly had 130 seats, with the Liberals holding 48, NDP 25, and PCs 52 after the 1985 election.
A formal accord between the Liberals and NDP ensured stability for two years in exchange for policy concessions.

Overview

The 33rd Legislative Assembly of Ontario marked a pivotal shift in provincial politics, ending the longest continuous run of one party in Canadian history. After 42 years of Progressive Conservative governance, the 1985 provincial election resulted in a minority legislature that ultimately brought the Liberal Party to power.

This Assembly convened on November 15, 1985, and lasted until May 1, 1987, setting the stage for significant policy changes and inter-party cooperation. The political realignment was made possible through a formal accord between the Liberals and the New Democratic Party (NDP), allowing David Peterson to become Premier despite not winning the most seats.

Frank Miller became leader of the Progressive Conservatives and Premier in May 1985 but led a minority government with 52 seats out of 130.
The 1985 Ontario general election was held on May 2, resulting in the PCs winning 52 seats, Liberals 48, and NDP 25, with no majority.
David Peterson was sworn in as Premier on June 26, 1985, after the Liberals and NDP signed a two-year accord to support a Liberal government.
The Assembly met at Queen’s Park in Toronto, the seat of Ontario’s legislative power since 1893, during this transitional political era.
Key legislation passed included reforms to rent control, environmental protections, and human rights policies, reflecting the NDP’s influence under the accord.

How It Works

The functioning of the 33rd Legislative Assembly was shaped by its minority status and the unprecedented Liberal-NDP agreement, which redefined how governance could operate without a majority.

Term: The Assembly officially ran from November 15, 1985, to May 1, 1987, following the dissolution of the legislature ahead of the 1987 election. This two-year session was unusually short due to the minority arrangement.
The Liberal-NDP accord was a formal agreement lasting two years, ensuring the Liberals could govern in exchange for implementing specific NDP policy priorities.
Confidence votes were critical, as the government could fall if it lost the support of the majority; the accord guaranteed NDP support on these key votes.
Committee work intensified during this period, with joint Liberal-NDP policy committees formed to oversee the implementation of shared legislative goals.
The Speaker of the Assembly was Hugh E. Mackenzie, who maintained neutrality while managing debates in a politically tense environment.
Legislative sessions were held in four parts over the two years, with prorogation used strategically to manage political timing ahead of the 1987 election.

Comparison at a Glance

A comparison of the 33rd Assembly with previous and subsequent legislatures highlights its unique political dynamics and short duration.

Legislature	Years Active	Majority/Minority	Leading Party	Seats Held
31st (1977–1981)	1977–1981	Majority	Progressive Conservative	70 of 125
32nd (1981–1985)	1981–1985	Majority	Progressive Conservative	70 of 125
33rd (1985–1987)	1985–1987	Minority	Liberal (with NDP support)	Liberals: 48 of 130
34th (1987–1990)	1987–1990	Majority	Liberal	95 of 130
35th (1990–1995)	1990–1995	Minority	NDP	74 of 130

This table illustrates how the 33rd Assembly was an anomaly: a short-lived minority government that enabled a dramatic shift in power. Unlike the long-standing PC majorities before it or the Liberal landslide that followed in 1987, this Assembly relied on cooperation rather than dominance.

Why It Matters

The 33rd Legislative Assembly reshaped Ontario’s political landscape and demonstrated that minority parliaments could function effectively through negotiated agreements. Its legacy influenced future minority governments in Canada, including federal and provincial examples in the 2000s.

The Liberal-NDP accord became a model for future coalition-style governance, showing that parties could collaborate without formal mergers.
It ended 42 years of Progressive Conservative rule, marking the longest single-party reign in Ontario’s history and proving voter sentiment could shift dramatically.
The Assembly passed significant legislation on environmental protection, including the creation of the Ministry of Environment and Energy.
David Peterson’s government introduced rent control reforms and expanded human rights protections, responding to NDP priorities in the accord.
Its success paved the way for the 1987 Liberal majority victory, where they won 95 seats, demonstrating public approval of the prior government’s performance.
The Assembly highlighted the importance of confidence-and-supply agreements in Canadian parliamentary systems, influencing later minority governments federally and in other provinces.

The 33rd Legislative Assembly remains a landmark moment in Ontario’s democratic evolution, illustrating how political innovation can emerge from electoral deadlock.