When Catherine McAuley was an heiress, she made two resolutions, She made sure that her inheritance was used for the relief and that she would build a refuge for distressed women of good character.

The House of Mercy, a some what huge building on the corner of Baggot and Herbert Streets, Dublin, officially opened on September 24, 1827, Feast of Our Lady of Mercy. The house is where the poor would be visible to the rich, at the House of Mercy, young hopefuls were trained in needlework, laundry, and other domestic services, Careful training improved job possibilities and provided a ladder upwards. education of women was also acknowledged to incalculable good not only to them, but also to society. in her mission of service, she wanted to provide means for unprotected girls and women to develop beyond that criticism.

She turned her attention also to the patients of Sir Patrick Dunn's Hospital, confinement in early 19th Century hospitals was a last resort. Patients were sent when they were expected to die. Catherine who had nursed so many through their last illness knew first hand the fears that beset the sick and dying. She wanted to comfort and assist hospitalized Catholics whose spiritual needs were so neglected. To gain permission of Protestant officialdom, she arrived in her carriage accompanied by other ladies of fashion. Later these visitors from the House of Mercy became the first Catholic religious to minister there. When cholera struck Dublin in 1832, Catherine and her sisters nursed the sick day and night. Sir Patrick Dunn's hospital had the lowest death rate of the epidemic. He attributed much of this success to the unflagging care of the Sisters. (This pattern of response brought Sisters of Mercy to the field hospitals of Crimea in Europe and those of the Civil and Spanish American Wars in the United States.)