This paper explores the relationship between 'process' quality characteristics in English pre-school centres and the developmental progress made by children between the ages of 3-5 years. A nationally representative sample of 141 English pre-schools participated in this study with longitudinal pre- and post-test measures taken from 2857 children at ages 3 and 5. Centre quality was assessed using two observational instruments, the revised version of the Early Childhood Environment Rating Scale [Harms, T., Clifford, M., & Cryer, D. (1998). Early Childhood Environment Rating Scale, Revised Edition (ECERS-R). Vermont: Teachers College Press] and a new English curriculum extension to it [Sylva, K., Siraj-Blatchford, I., & Taggart, B. (2003). Assessing quality in the early years: Early Childhood Environment Rating Scale-Extension (ECERS-E): Four curricular subscales. Stoke-on Trent: Trentham Books]. This new instrument was developed specifically for assessing the curricular aspects of quality, including pedagogy, in pre-school centres subject to the English national Early Childhood Curriculum. Multi-level statistical analyses revealed that quality of centre-based provision as measured by the ECERS-E was a significant predictor of children's development at entry to school after controlling for pre-test, child characteristics and family background. This study demonstrated that the ECERS-E is a reliable instrument for assessing the educational aspects of process quality and is a significant predictor of children's cognitive/linguistic progress. In contrast, the ECERS-R had a stronger relationship with children's socio-behavioural progress in the pre-school period. © 2006 Elsevier Inc. All rights reserved.