Parents As First Educators president Teresa Pierre announced a petition Monday to Catholic school board trustees and is calling on Catholic voters to sign it.
The petition asks the trustees to demand the Ontario English Catholic Teachers' Association not send Catholic teachers to the parade.
Pierre says the event is inconsistent with what the church teaches about homosexuality.
She says Catholic parents expect a Catholic teachers' union to support the teachings of the church on marriage and family, adding that the parade "breaks nudity laws and participants promote homosexual activity."
The union, which represents about 34,000 teachers, hasn't commented on the petition.
(680News, The Canadian Press)
Note to readers: This is a corrected story. A previous version said the parents' group was urging Catholic school trustees to sign the petition.