The nineteenth-century Roman Catholic missionary endeavour in New Zealand had its origins in a society of priests from Lyon, known as the Marists. The Marists’ mission has been deemed a failure due to its ongoing financial problems, its reputation for having abandoned Māori adherents, and its less visible impact compared to the Anglican Mission. This thesis examines the challenges facing the pioneer Marist priests in New Zealand and asks the question: was the Mission indeed a failure? The answer lies in the correspondence of the French Marists themselves, a largely untapped historical source which contains a different view of early New Zealand contact and religious history from that of the Church Missionary Society (CMS) evangelists. ‘The Struggle for Success’ consists of three parts examining the Mission before, during and after the pioneer phase. The first describes the Marists’ early influences and religious formation in France, which serve to elucidate the missionaries’ raison d’être and provide an historical context for the Mission. It is also an important attempt at a prosopography of men whose early lives were barely documented, and whose connection with contemporaneous and historical France, and the Lyon area in particular, would greatly affect the missions in Oceania. The subsequent comparative mission history in Part Two highlights the difficulties and conflicts that affected the progress of the Marist Māori Mission in New Zealand compared with other Christian missions in Oceania, notably the CMS in New Zealand and the early Marists in Wallis, Futuna, Tonga and New Caledonia. It describes the factors leading to the alleged failure of the Marist Māori Mission and demonstrates that hardships and struggle were the common lot of pioneer missionaries in Oceania. But the Marists on the Māori Mission had the added obstacles of being Frenchmen in a British colony, ascetics surrounded by and dependent on commerce, and dutiful religious under the authority of overburdened bishops. Irish immigration into New Zealand distorted the original aims of the French Marist missionaries, and Māori politico-religious initiatives to combat the devastating impacts of British colonialism essentially quashed Marist hopes that Māori would become a decidedly Catholic people. Having considered the obstacles to success, the thesis discusses in Part Three how the pioneer Marists understood success and conversion. In retrospect, it is clear that the missionaries underestimated the tenacity of early Māori catechists, but the CMS in New Zealand and Marists throughout Oceania were equally insensible in this respect. Finally the thesis offers an assessment of the mission’s overall success taking into account the revival of the Marist Māori Mission in the late 1870s and its continuation into the twentieth century. The social, cultural and political complexities of missionary endeavour demand a less rigid evaluation of missions than has been previously offered; and success and failure are problematic terms for the pioneer Marist Māori Mission because evangelisation was and is a work in progress.