The risk of exclusion from the labour market is the highest among the low educated young. This research analyses the long-term effects of attending pre-school before the children are 3 years old in Spain. The effects are measured when the individuals are adolescents and attend secondary school. The dependent variables are educational performance and risk behaviours such as violence and aggressivity, and consuming alcohol and marihuana. Household socioeconomic position is measured by mother’s education and disposable income. The information is captured from a survey on 3000 students and their families, the families answering retrospective questions related to child care. Data are analysed using statistical techniques designed to control endogeneity and sample selection effects. The paper deals with the controversy over the long term effects (positive and negative) of pre-schooling and the potential effect in reducing inequalities and social exclusion. My preliminary results estimate a significant effect in improving educational performance and reducing risk behaviours. However, those beneficial effects are lower among adolescents residing in the lower status households.