A memory of her father's strong and practical love for the poor and his untiring patience in instructing them in the great mysteries of the Catholic faith, coupled with her own experiences of orphanhood, extreme poverty, and the oppression of her faith, enkindled in Catherine McAuley a call best expressed in the mandate of Jesus, "Be merciful as your Heavenly Father is merciful."

When, as a young woman she was adopted by Mr. and Mrs. William Callaghan and because of them knew material security and relative freedom to practice her faith, she began immediately to instruct the poor as her father had done and to use whatever resources she had to alleviate their needs. One day Mr. Callaghan asked Catherine what she would do after he was dead. She shared with him a desire that had been developing through the years: "To rent a small house and support a few women whom she could instruct and teach to work." Three years later Mr. Callaghan died having bequeathed to her nearly all his fortune. She received it as a gift from God to enable her to extend her work among the poor.

Discussion with trusted friends and advisors among the clergy, and consultation with Dr. Daniel Murray, Archbishop of Dublin, regarding her desire to do some lasting good for the poor, resulted in Catherine's decision to build a large house in a fashionable residential district of Dublin. The house would serve as school for the poor, a shelter for homeless young women, and provide a center from which the needs of the poor in the hospitals and homes of Dublin could be administered. Catherine would also live there and invite other lay-woman who were anxious to devote their leisure time to charitable work, to join her in teaching the children and participating in the in the activities of the house.

A site on the corner of lower Baggot Street and Herbert Street was selected for its advantage of bringing the needs of the poor to the attention of the wealthier classes of the neighborhood. It was also near the Kildare Place Schools which provided excellent free education to the poor, but were recognized for their practices of Protestant proselytism. Construction work on the first Home of Mercy began in 1824. Catherine had sketched out her requirements for the contractors. "The building was to be plain in appearance, and to contain large airy school-rooms, several big dormitories to provide lodging for young women, a lofty room suitable for an oratory, and finally some small rooms for herself and other ladies who might choose to work with her." On September 24, 1827, classes were taught and some women were given shelter for the first time.

Catherine had meanwhile gathered a nucleus of women who daily visited the poor and sick in their own homes. These women now came to the Home of Mercy to live and to preside over the various works of Mercy undertaken. In addition, there were a number of women who lived in their own homes and spent some hours each da in works either in or related to the Home of Mercy. Hundreds of poor children were educated there. Homeless young women were given shelter and taught both skills and personal habits which would enable them to gain productive employment, and in time, to establish strong Christian families. Great care was taken to place them in situations for which tehy were adequately prepared in order to establish good character references for the future. For this end, an employement agency was organized within the Home of Mercy.

From a "Life of Mother McAuley," by Mother Timothea Elliott, R.S.M., in the Documents of the Foundation of the Religious Sisters of Mercy of Alma.