The party was formed in 1989 as a reaction to then-Premier Robert Bourassa invoking the "Notwithstanding clause" of the Canadian constitution to override a Supreme Court ruling overturning parts of the Charter of the French Language (commonly known as "Bill 101").

The party first came to prominence in the 1989 general election, when it won four seats on Montreal Island in the National Assembly with 3.7% of the popular vote.

(This arrangement was repeated in later elections when Action démocratique du Québec won fewer seats in the National Assembly than required for official status).

The four members took an active role in National Assembly debates, most notably when Party leader Robert Libman made headlines by using his parliamentary privilege to reveal the details of confidential, money-losing contracts signed between Hydro-Québec and some of Quebec's aluminum producers.

[4] The party's published financial statements, however, reported that only $7795 in membership dues were collected in 1990, down 75% from 1989 and enough to account for only 1,559 dues-paying members.

In addition to the infighting and defections, the Equality Party's raison d'être arguably vanished when the government amended the Charter of the French Language in 1993 to allow for more prominent English language text on commercial signs, so that the law no longer needed the use of the "notwithstanding clause" to withstand constitutional challenge.