This chapter surveys how poverty has been understood historically in the UK since 1900. On the one hand, poverty has been viewed as a large-scale structural phenomenon. Understandings of poverty have been significantly advanced through social surveys. Significant developments have included the collection of empirical data, the elaboration of poverty lines, the use of random sampling, the move from concepts of absolute to relative poverty, and the development of methodologies and theories based on poverty dynamics. However, poverty has also been repeatedly viewed as a residual personal or family problem. In the modern period, such concepts have included, in the UK, the social residuum of the 1880s, the social problem group of the 1920s, the problem family of the 1950s, the cycle of deprivation of the 1970s, the underclass of the 1980s, the socially excluded of the 1990s, and the troubled families of the early 21st century. The chapter looks at three landmarks in the history of poverty in the UK – the Rowntree survey (1901); Peter Townsend’s theory of ‘relative deprivation’; and research on poverty dynamics from the 1990s – and shows how each was both preceded by, and followed by, rival readings of poverty.