From the age of 14 she studied theatre: at Studio XV directed by Gérard Vleminckx, then with teachers Aario Marist and Henri Norbert. She made her debut in 1950 with Norbet's company, le Trait d'Union, in Ces dames aux chapeaux verts. The following year she portrayed Dounia in Dostoyevsky's Crime and Punishment directed by Marist. With the arrival of television in 1952, and until the 1980s, she took part in several televised plays, performing French, Russian, English and Italian authors as well as the Québécois Pierre Perrault, Françoise Loranger and Marcel Dubé, whom she also championed in theatre.
Her countless stage performances include roles in works by Dubé: les Beaux Dimanches, Au retour des oies blanches (Comédie canadienne, 1965 and 1966) and Bilan (Théâtre du nouveau monde, 1968). Since the 1960s, she drew attention in comedies such as Goldoni's La Locandiera (Nouvelle Compagnie Théâtrale, 1965) and Feydeau's la Dame de chez Maxim's Théâtre du rideau vert, 1970), and also in dramas such as Chekhov's, Uncle Vania (L'Égrégore, 1966) and later The Cherry Orchard (Théâtre du Trident/TRV, 1988).
A passionate interpreter of Tennessee Williams, from Cat on a Hot Tin Roof (Trident, 1972) and the tragic Blanche Dubois in A Streetcar named Desire (Théâtre de l'Atelier, Paris, 1975 and Trident, 1984), she also performed Claudel and Genet. She contributed to premiers by Jovette Marchessault, la Saga des poules mouillées/Saga of the Wet Hens (TNM, 1981) and Anaïs dans la queue de la comète/Anais in the Comet's Wake (Quat'Sous, 1985). She portrayed a best-selling author in the premiere of Passage de l'Indiana at the Festival d'Avignon (Théâtre UBU/CNA/Festival d'Avignon, 1996) by Normand Chaurette. Always active, she toured in Michel Tremblay's Albertine, en cinq temps (Espace GO, 1995-99), then with Wajdi Mouawad's Incendies (FTA/Quat'Sous, 2003-2005), and triumphed again in la Promesse de l'aube (Espace GO, 2006), based on Romain Gary, under the direction of her husband, André MELANÇON.
Her television career included numerous drama series: Marcel Dubé's le Monde, Entre midi et soir, le Temps d'une paix, Monsieur le ministre, and le Volcan tranquille. She appeared in films: Denys Arcand's Jésus de Montréal, Yves Simoneau's Dans le ventre du dragon, Robert Favreau's Nelligan, Michel Langlois' Comme un voleur (winning the Prix Guy-L'Écuyer) and Jean-Claude Lauzon's Léolo.
André Lachapelle was made a Chevalier of the National Order of Quebec (1998) and an Officer of the Order of Canada (1985).