During the next seven years, Lasance served as curate in various parishes in the Archdiocese of Cincinnati including churches in Kenton, Reading, Dayton, Lebanon, and Monroe, Ohio. He also served as chaplain at Our Lady's Summit, in East Walnut Hills, in Cincinnati. Ill health forced him to relinquish parish work in 1890; from then on, he lived a "retired, semi-invalid existence" at St. Francis Hospital, Cincinnati, writing various books on spiritual subjects and serving as spiritual director of the Tabernacle Society.
Manual of the Holy Eucharist: Conferences on the Blessed Sacrament and Eucharistic Devotions
Mass Devotions and Readings on the Mass
Peace, Not as the World Gives
Pious Preparation for First Holy Communion: With a Retreat of Three Days
Prayer Book for Religious
Sermons on the Blessed Sacrament: and Especially for the Forty Hours' Adoration
Short Visits to the Blessed Sacrament
He also compiled and edited the Blessed Sacrament Book (1913).
His works were translated into numerous languages. In total, his texts were published in the millions. He refused all compensation for his work and asked that any profits be donated to charity or toward providing his works free of charge to those unable to purchase them. For his devotional works, he was given a special blessing by Pope Pius XI on May 10, 1927.
A number of Lasance's writings have been reprinted and are currently available from various traditionalist Catholic publishers, including My Prayer Book, Manna of the Soul, Blessed Sacrament Book, and The New Roman Missal (reprinted in 1993 by Christian Book Club of America), which at present is one of the most popular hand missals favored by American traditionalist Catholics.