Migration into Britain is not a contemporary phenomenon; yet, nineteenth-century British migration history is disproportionately weighted towards those who left. In the nineteenth-century, hundreds of thousands of migrants arrived and settled in England and Wales. Yet, important gaps remain in the literature with respect to how migrants settled, integrated, and interacted with the host society. This thesis utilises a datadriven approach to investigate the composition and behaviours of foreign-born persons in England and Wales during the period 1851-1911 and establish who they were, where they came from, and what they did after arrival. Specifically, this thesis asks ‘to what extent did the foreign-born population integrate or segregate from the nativeborn population?’ Using the recently released Integrated Census Microdata (I-CeM), this thesis is the first to analyse the entire foreign-born population of England and Wales at an individual-level. Key themes considered in this thesis includes the demography and structure of foreign-born households, socio-economic composition,
and spatial distribution of migrants. Two case studies, one from Newcastle upon Tyne, and another from East London, are used to contrast the residentially segregating behaviours of the migrant populations. A series of key findings are presented in this work. For example, less than twenty per cent of the migrant population lived exclusively with other migrants, indicating a tendency to interact with the host society. Taken holistically, therefore, this thesis establishes the national landscape of migrant composition, activity, and settlement, and provides a large-scale reconstitution of the foreign-born population and its different components.