This thesis contributes new and unique evidence to the debates surrounding population changes in late medieval England. Through the use of documentary evidence it investigates both mortality and life expectancy rates of the students of Winchester College and New College, Oxford, from 1393 - 1540. In so doing it provides the largest single closed population group examined to date for this period and, importantly, the first sample to follow the experiences of children and adolescents. Source materials are analysed, with particular attention paid to their applicability to the study. Research methodology is also considered, in particular database construction and design, essential parts of the manipulation and analysis of such a large dataset. The records of the two colleges are examined in detail, and analyses presented focusing on the admission rates, departure information and mortality rates within each institution. The latter identified changes across the study period and also possible correlations with national disease outbreaks. Analyses of age data for the scholars contribute valuable interpretations of how the two institutions functioned over the course of the study period and how their administrative practices responded to changing mortality patterns and recruitment demands. Life expectancy rates for the scholars are calculated and analysed. Significantly the life expectancy rates of the Winchester sample demonstrate a better experience than that of previously published monastic samples. The Winchester sample follows scholars out into the wider medieval population (post-education), perhaps providing data that is more representative of the wider community than the monastic studies. Interpretations support the hypothesis that underlying mortality patterns were the cause of changes in life expectancy, and that these patterns were likely to be observed across the population. The conclusions from this large and original dataset are placed within the context of the wider historiographical debates. The need for new, relevant and more diverse samples is emphasised to advance the interpretations of population changes and the economic and social history of late medieval England.