Catherine went first to live with a maternal uncle, Owen Conway, and later joined her brother James and sister Mary at the home of William Armstrong, a Protestant relative on her mother's side.

In 1803, McAuley became the household manager and companion of William and Catherine Callaghan, an elderly, childless, and wealthy Protestant couple and friends of the Armstrongs, at their estate in Coolock, a village northeast of Dublin.

On the feast of Our Lady of Mercy, 24 September 1827, the new institution for destitute women, orphans, and schools for the poor was opened and Catherine McAuley, with two companions, undertook its management.

McAuley never intended to found a community of religious women; her initial intention was to assemble a corps of Catholic social workers.

Catherine and two other women, Anna Maria Doyle and Elizabeth Harley, entered the novitiate of the Presentation Sisters to formally prepare for life as religious in September 1830.

[9] Between 1831 and 1841 she founded additional communities in Tullamore, Charleville, Cork, Carlow, Galway, Limerick, Birr, Bermondsey and Birmingham and branch houses in Kingstown and Booterstown.

[10] Shortly thereafter, small groups of sisters left Ireland to establish new foundations on the east and west coasts of the United States, in Newfoundland, Australia, New Zealand, and Argentina.