The idea of exploring the life of Mary MacKillop in New South Wales came from the members of the Mary MacKillop Committee. Several sisters were active in researching and recording the years 1880-1909 and I was asked to bring this to fruition. Research for these years had been undertaken by Lynette Raftery rsj, Barbara White rsj and Clare Burgess rsj and I have added my own research. Bridie O'Connell's reflection on the final years of Mary MacKillop's life provides a fitting conclusion to the story. This book, One Door Closes Another Opens, aims to tell of the endeavours of Mary MacKillop in spreading the Gospel, sending out her sisters to care for and educate the neglected children in the poorest areas of the city of Sydney, particularly the slum areas around the part known as The Rocks on the shores of Sydney Harbour. These pioneer sisters were sent, too, to far flung towns and villages throughout New South Wales in the Dioceses of Sydney and Armidale, both of which encompassed huge areas. Mary visited the sisters, supported, encouraged, and assisted them in their work for God and his people. She journeyed by every known conveyance then available, in every kind of weather, often enduring snow, torrents of rain, blazing sun and heat and very often suffering poor health. All this was for the glory of her good God and for his children and to bring the message of his love and mercy to people in these isolated places. The withdrawal of Mary MacKillop's sisters from Bathurst in 1876 closed their work there but it also saw the birth of a diocesan congregation of the Sisters of St Joseph under Bishop Quinn. The Bathurststory has been well told by Dr Marie Crowley in her notable work Women of the Vale which is highly recommended to readers. When Mary MacKillop and her sisters withdrew from Queensland at the end of 1879, they were welcomed into New South Wales by Archbishop Vaughan of Sydney and Bishop Torreggiani of Armidale. Hence the title, One Door Closes Another Opens. This work is a story of heroism, not only on the part of Mary, but also on the part of those pioneer sisters and the generous people who supported them. All of them laboured to teach and strengthen the catholic faith wherever they lived and worked. We thank God for them and dedicate this work to their memory. I wish to acknowledge the assistance given by Mr Gary Hayes who read the original draft of this work and gave many helpful suggestions. Sister Marie Therese Foale rsj gave of her time and considerable talents as an author to help to bring the work to a conclusion. To them, my grateful thanks.