At fourteen years Lagace was organist at the Seminary of Saint-Hyacinthe, where he studied with Conrad Letendre. In 1948 he replaced Raymond Daveluy to the organ of Saint-Jean-Baptiste Church, where he was professor of in 1950.At the same time he studied with Yvonne Hubert (piano) and Gabriel Cusson (harmony and counterpoint). He could then study the blind in Paris André Marchal (1954-55) and in Vienna with Anton Heiller (1956). At the same time he studied harpsichord with Isolde Ahlgrimm , Eta Harich-Schneider and Ruggiero Gerlin.
Back in Montreal (Canada) (1957), he became a teacher at the Music Conservatory of the city (1957-78) and at Concordia University (1978). During the summer he taught at the Centre include musical cammac the Choate Music Seminars Wallingford, Conn.., The Centre d'Art d'Orford JMC, the Académie d'été de Saint-Hubert in Belgium , the Académie d'orgue in Saint-Die-des-Vosges France. Lagace has many students who formed his wife Mireille, his daughter Genevieve, Luc Beausejour, Helen Dugal , Dom André Laberge, Lucien and Réjean Poirier , Marc-André Doran and Wilhelmina Tiemersma.
Founding member of the Ars Organi group, he has actively contributed to the revival of the classic organ in North America. He acted as a jury member in several international competitions in England, Belgium, France, Ireland and Canada. So he was in 1973, 1976 and 1979 jury member for international organ competition in the context of the Early Music Festival in Bruges
As an organist he received international acclaim and also gave numerous recitals in the United States and Europe, of course, in Canada. Since 1966 he has been professor of the organ in the sanctuary Marie-Reine-des-Cœurs in Montreal. He also has a vast number of works to include.
Even though he has all the great works of the organ repertoire played, he is still mainly as a specialist of Baroque music, and more specifically of Johann Sebastian Bach considered. He has twice performed the inclusion of the integral of all his organ works, the organ of the Church of the Immaculate Conception in Montreal (1975-77 and 1987-89). Together with his wife he has the complete works for organ by the same church Dietrich Buxtehude included (1978-79). He has also a lot of work by Johannes Brahms recorded.
- Prix Denise-Pelletier (Quebec Government) 1978
- Prix de musique Calixa-Lavallee 1989
- Member of the Order of Canada, 1985
Next, a selection of recordings by Lagace.
- JS Bach - J. Brahms: 11 Chorals et Fugue en la b, Titanic Records, 1978
- S. Scheidt - Tabulatura Nova III extraits the Tabulatura Nova I Disques Calliope, 1980
- JS Bach - Orgelbüchlein / Complete Little Organ Book, Disques Analekta , 1991
- JS Bach - Chorals Leipzig, Disques Analekta, 1991
- Musique allemande du 17 ° siècle, Titanic Records, 1991
- JS Bach - JS Bach: Goldberg Variations BWV 988 à l'orgue, Disques Analekta, 1995