On September 4, 2012, Marois led her party to minority victory in the Quebec general election, thus becoming the first female premier in the province's history.
However, her party was defeated 19 months later in the 2014 Quebec general election, an election that she herself had called.
With the return of the PQ to government in 1994, premiers Parizeau, Bouchard and Landry appointed Marois to senior positions in the Quebec cabinet.
She was instrumental in crafting policies to end confessional school boards in the public education system, she restructured the tuition system in post-secondary education, implemented a subsidized daycare program, instituted pharmacare and parental-leave plans and slashed the Quebec deficit under Premier Bouchard's "deficit zero" agenda.
In 2001, Premier Landry appointed her Deputy Premier of Quebec, becoming the third woman after Lise Bacon and Monique Gagnon-Tremblay to assume the second-highest role in the provincial government.
Following two failed leadership runs in 1985 and 2005, Marois briefly left political life in 2006.
Her electoral defeat was despite calling an early election for April 7, 2014 in a purported gamble to obtain a majority government.
Ultimately, her party lost with the Liberal party gaining a majority government, and Marois, herself, losing her own riding.
Her defeat marked the shortest stay of any Quebec provincial government since Canadian Confederation.As Premier, Marois closed down Quebec's only nuclear reactor, ended asbestos production in Quebec, and pacified the province's turbulent campuses.
Her government's highest profile initiative was the proposal of a controversial Quebec Charter of Values which would have banned the province's 600 000 government employees from wearing religious symbols including turbans, Islamic veils and Jewish kippahs.
However, the crucifix (notably, the one hung by above the Speaker's chair in the provincial legislature) would not have been banned under the Quebec Charter of Values.