This thesis contributes to the literature on the French Catholic Marist mission in New Zealand by providing the first critical in-depth biography of one of the early French missionaries, Antoine Marie Garin (1810-1889). It emphasises the importance of the Marists’ position as outsiders in nineteenth-century New Zealand society. As neither ‘colonising’ British settlers, nor ‘colonised’ Maori, the Marists were in a special position to view events unfolding in the mid-nineteenth century, when New Zealand was changing from a Maori-dominated to a predominantly Pakeha-dominated world. The records which the Marists kept of their experiences, including diaries, letters, memoirs and annals, have the potential to provide a significant contribution to New Zealand historiography, and remain relatively untapped. As a biographical study, this thesis uses the framework of Garin’s life story to add insight to the intercultural dynamic in nineteenth-century New Zealand. The thesis begins with an exposé of the theory used to examine the intercultural dimension in Garin’s experience. Garin’s life in New Zealand was a tale of cross-cultural encounter occurring within two cultural-social paradigms: the Maori-Pakeha paradigm, and the Catholic-Protestant settler paradigm. With respect to the Maori-Pakeha paradigm, it is argued that Homi K. Bhabha’s theory of hybridity provides an innovative framework within which to study early interaction between Maori and Pakeha. The concept of hybridity stresses the interdependence of coloniser and colonised, thereby recognising the existence of agency on both sides, and avoiding the binary opposition of ‘Maori’ and ‘Pakeha’ that continues to mark contemporary New Zealand society. Another postcolonial theory, that of diaspora, is used to illuminate Garin’s experience in settler communities. It is argued that religion can be the basis for a diaspora, and that the Catholics in nineteenth-century New Zealand had a diasporic consciousness because of their creation of separate Catholic institutions, and their connections to the wider Catholic world. Part Two of the thesis consists of the biography proper. It is framed as a cultural biography: a biography that seeks to illuminate not only the subject’s life, but also national history. Garin was a grassroots Catholic missionary, who, through talent, perseverance and a little luck, made a notable impact on New Zealand society, in particular in the area of Catholic education. However, even more important to his story was his ability to build bridges between cultures, and create communities of Maori and settler Catholics. Arguably, Garin’s greatest legacy is the diary that he kept while a missionary to Maori. This documents the everyday border crossing that was taking place between the Maori of Mangakahia and Garin himself in the hybrid society of 1840s’ New Zealand.