This chapter explores population data sets, which are statistics published by government agencies in a number of countries. They contain information about the characteristics of, or changes to, a population. For example, records of births, deaths, marriages, immigration and emigration. They are therefore a key source for making sound decisions about national policy. This chapter examines the nature of such data and questions how it might be useful at local level to those working alongside young children. The chapter invites early childhood educators to critically engage with broad based population studies to put locally contextualised Practitioner Inquiry into practice. The author considers ways this approach may offer an insightful method for early childhood educators and leaders to examine developing national and locally determined trends – trends which can positively impact on children’s life experiences and shape pedagogical practice.