Abstract
This study investigates the factors influencing quality in Early Childhood Education and Care (ECEC) in Spain focusing on the 0–3 age group. The research draws on data collected using the ITERS-3 (Infant/Toddler Environment Rating Scale, 3rd edition) instrument from 62 centers across Spain. Using nonparametric statistical analysis, particularly decision tree analysis, the study identifies key factors influencing the quality of ECEC environments. The results emphasize the significance of variables such as “Peer Interaction,” “Encouraging children to communicate,” “Schedule and transitions,” “Free play,” and “Diapering/toileting” to explain the quality of ECEC settings. The findings offer insights into the importance of promoting positive peer interactions, encouraging communication, and providing flexible scheduling and free play for ECEC quality improvement. Furthermore, the study explores how the quality of ECEC settings differs depending on center ownership (public, private, or subsidized ones—private but publicly funded). It reveals distinctions in the factors that contribute to quality across these ownership categories. These findings provide valuable insights for educators, policymakers, and stakeholders in enhancing ECEC quality and informing future research directions in the field. Overall, this study not only highlights critical quality indicators for ECEC for children under three but also offers a foundational evidence base to guide targeted educational practices and policy interventions, supporting equitable and high-quality access in Early Childhood Education.