Studies of the institutionalisation of children in eighteenth century Britain and in early colonial Australia have focussed on its relationship to industrialisation, ideas of childhood and family, and the government of the poor. My thesis contributes to these analyses by connecting the institutionalisation of children to the process of colonisation within Britain and beyond in this dynamic period of economic, political, social and intellectual change. In doing so, I explore the role of child institutional practices in the formation of societal structures and social relations in colonial and metropolitan locations, and their resulting impact on the social orders and hierarchies within each location. This thesis undertakes a comparative historical analysis of child institutional practices in London and colonial New South Wales c. 1750-1828. In order to do so, six case studies are conducted. The first three case studies focus on institutional practices in London: children under apprenticeship in the Bridewell Hospital, orphan children admitted into the Foundling Hospital, and children tried through the Old Bailey. By exploring the social, economic and political climate of the period, including ideas of moral and penal reform and their association with philanthropy, these chapters lay the foundation for understanding how and why child institutional practices were established and operated during the late eighteenth century. The last three case studies focus on the adaptation of these pre-existing institutional practices into the new infant colony of New South Wales, with specific focus on the impact of transportation on children sent to the colony between 1790-1799, the establishment of the Male and Female Orphan Institutions, and the lasting impact of these institutional practices on the child inmates. To conduct the case studies, a range of primary documents are utilised to gain insight into contemporary attitudes, debates, and policies relevant to the institutionalised treatment of children. These include government policies, institutional charters including any rules and regulations relating to individual institutions, and cotemporary publications and correspondence by benevolent individuals, reformers and campaigners. In addition to this, records from British and Australian archival repositories were drawn upon to establish study samples for the case studies. This includes the Proceedings of the Old Bailey, an online database which provides the trial details for defendants indicted and/or convicted of a criminal offence at the Old Bailey between 1674-1913, the State Records of New South Wales, including the Convict Indexes and Admission Records for the Male and Female Orphan Institutions, and a digitalised copy of the Census of New South Wales - November 1828. These repositories are used to establish previously unexplored study samples of children in London and colonial New South Wales and to provide statistical and personal insight into the confinement of these children through child institutional practices in both locations. While child institutional practices in London were designed to raise children to ‘their position in the lower stations of society’, their implementation in an infant colony with a more ad hoc social order provided the opportunity for some former inmates to transcend social boundaries in spite of their backgrounds. In concluding, I consider the implication of these findings for our understanding of the early history of child institutional practices and their role in the formation of British and colonial societies.