Important claims have been made for what has been termed the dynamic analysis of poverty. However, apart from references to Rowntree's mention of the life cycle in his 1901 survey, the earlier history of these approaches has been neglected. This article seeks to document the historical origins of the two main UK birth cohort surveys—the 1946 National Survey of Health and Development (NSHD) and the 1958 National Child Development Study (NCDS). It locates their origins within wider historical contexts, and shows how their focus changed. In the absence of guaranteed long-term funding, especially for the NCDS, each generation of researchers needed to make a fresh case for a follow-up survey. It is this need, and for this reason, that the birth cohort surveys can shed so much light on the history of social science research in post-war Britain.