The EPPNI Project is a large scale, longitudinal study which began in 1998 to investigate the links between children’s preschool experience and their later cognitive, social and emotional development. The study explored the characteristics of all main types of pre-school provision attended by 3 to 4 year olds in Northern Ireland.  By following the progress of over 800 children, this project has found significant results relating to the short and long term benefits of preschool experience.