 In 1825, Darby was ordained deacon of the established Church of Ireland and the following year as priest.Darby became a curate in the Church of Ireland parish of Delgany, County Wicklow, and distinguished himself by persuading Roman Catholic peasants in the Calary district within this parish to abandon the Catholic Church.The well-known gospel tract "How the Lost Sheep was Saved"  gives his personal account of a visit he paid to a dying shepherd boy in this area, painting a vivid picture of what his work among the poor people involved.