Information on the characteristics of the parents, families and children in the Effective Provision of Pre-school education (EPPE) project was collected by parental interview at the start of the study. This paper shows how this information was used to describe the sample in terms of the parents (labour market participation, socio-economic characteristics, qualifications, marital status and age), the family (composition, ethnicity and language), the child's health, development and behaviours, the child's activities in the home, the use of pre-school provision and childcare history.