Franciszka was educated privately by governesses, remaining indifferent to religion until she met a zealous Capuchin priest, who prepared her for her first Holy Communion, at which time she offered herself completely to God.
She strongly desired a religious vocation, but because her father opposed the idea, she had to wait to execute her mission of founding a new religious congregation. Having submitted a petition on 1 October 1873, Siedliska founded her new congregation in Rome on the first Sunday of Advent in 1875, having received the blessing of Pope Pius IX. Siedliska named her order after the Holy Family, viewing it as the perfect model of total abandonment to the love of God. The congregation spread rapidly to Poland, England, France, and, in 1885, the United States.
Siedliska led eleven sisters to found a community in Des Plaines, moving to Pittsburgh ten years later in August 1895.
Having taken the name "Mary of Jesus the Good Shepherd", Siedliska devoted herself to her congregation, presiding at religious exercises, holding conferences, and writing letters of encouragement to her more than 29 foundations. Her efforts slowly drained her of physical strength and Franciszka Siedliska died in Rome on the Feast of the Presentation of Mary, 21 November 1902.
Thus I envisioned our life in Nazareth as a life of love externally given to work, service, performance of whatever Our Lord may require. Franciszka Siedliska was beatified by Pope John Paul II on 23 April 1989, 86 years after her death.
In 2000, the pope also beatified eleven sisters of the institute who had been murdered by the Gestapo in August 1943 in present-day Belarus, the Blessed Martyrs of Nowogródek.