The study analyses determinants of child outcomes in a cohort of children who participated in the Free Pre-School Year. Child outcomes are measured through a before-and-after assessment of children using the Early Development Instrument. The sample comprises 448 children in 70 early years centres. There are three main findings. First, children with more or better skills at the beginning of the study period tended to have more or better skills at the end of this period, and vice versa, indicating that the broad parameters of a child's progress during the Free Pre-School Year have already been set by the child's development during previous years. Second, child and family characteristics are the largest set of measured influences on child outcomes by comparison with the pre-school system, with social class being the single biggest influence. Third, there were significant skill gaps between children at the start of the Free Pre-School Year which remained unchanged or widened during the year. The main conclusion is that the measures required to improve child outcomes in pre-school need to extend well beyond the confines of the early years sector to include all influences, especially family and social class influences, on child development and need to begin at the start of the child's life. (author abstract)