Specialized preschool programs can enhance the development of vulnerable young children at risk of special educational needs (SEN). Less is known about the potential of early childhood education and care (ECEC) provided for the general population. This study includes 2,857 children attending 141 ECEC centres in England and 310 with no ECEC. ECEC quality and effectiveness were assessed. Children's scores on assessments of cognitive development, numeracy, and literacy, and teacher reports of socio-emotional problems at ages 5, 7, 11, and 16 years were used to identify risk of SEN (1 standard deviation beyond the mean). Trend analyses (none vs. low, medium, and high ECEC quality or effectiveness) examined impact of ECEC on risk for cognitive or socio-emotional SEN. Better quality and more effective ECEC reduced risk of cognitive SEN at 5, 11, and 16 years of age, with similar results for socio-emotional SEN. The discussion considers the consistency of the association between children's ECEC experience and risk for SEN, which is found for alternative measures of ECEC, quality derived from observations and effectiveness derived from progress in child outcomes. These different sources for the ECEC measures add credibility to the results. Also the implications for policy and practice are discussed including the recommendation for universal provision of high quality ECEC and ensuring that the most at-risk populations receive the best ECEC available.