Her biographer Katherine Burton writes that the “Catholic faith draws its chosen in many and varied ways. For Lucy the path led through music.” Lucy lived next to St. Vincent De Paul Church on 23rd Street, and she used to listen to the music coming from the church. Eventually she began visting the church, and one day a child asked her:
“Are you a Catholic?” Lucy shook her head. “Oh. No,” she said. “Then why are you kneeling in our church adoring the Blessed Sacrament?” asked the girl. Lucy stared at her, “Adore the Blessed Sacrament. But I don’t even know what that is. I just went there and knelt because I wanted to and because I really couldn’t help myself.”
A Catholic friend introduced her to Father Alfred Young, himself a convert and a Paulist who specialized in liturgical music. On December 18, 1865, she was received into the Roman Catholic Church at St. Paul the Apostle in Manhattan. Her mother was worried about how her daughter’s conversion would affect her own social standing, since the “social New York of the day had no use for Catholics.”
Like many young women of her social status, Lucy traveled in Europe. She stayed there for nearly three years. While she was there she encountered the Dominican order. The figure who particularly appealed to her was the sixteenth century Dominican mystic St. Catherine De Ricci. In Berlin she met a priest who became her spiritual director and to whom she expressed her growing interest in religious life. Burton writes:
She envisioned an order of nuns to whom women could go, women whose lives perhaps had not sufficient religious vitality and who did not know how to go about it for themselves, nuns who knew the world and its problems, whose time was taken up entirely with educational or hospital work.
She soon became a Third Order Dominican, a lay person who attempts to live out the order’s charism in the world. A few years later, at age thirty-five, she contacted Bishop Francis McNeirney of Albany about starting a Dominican community in Glens Falls, New York. He agreed, and she took the full Dominican habit along with two other women. She took the name Mother Mary Catherine De Ricci of the Sacred Heart. Her sister Isabel, a widow, also joined, taking the name Sister Mary Loyola of Jesus.