The Early Childhood Environment Rating Scale, Third Edition (ECERS-3), is widely used to assess preschool quality. However, concerns remain about its scoring structure, usage in different cultural contexts, and associations with structural quality indicators. This study explored the factor structure of the ECERS-3 and its relationship with teacher education, child-to-adult ratio, group size, and preschool size in 71 Swedish municipal preschools. Confirmatory factor analysis showed poor fit for both the single-factor modeland the original six-subscale structure. Exploratory factor analysis identified a better-fitting four-factor structure: Learning & Play Environment, Interactions & Order, Gross Motor, and Care & Hygiene. We further investigated whether adopting this revised factor structure influenced relationships between ECERS-3 dimensions and structural quality indicators. Analyses of associations with structural quality indicators showed that smaller group sizes were linked to higher quality in Gross Motor activities. Among preschools with group sizes below 15 children, smaller groups were also associated with higher quality in Learning & Play Environment, Care & Hygiene, and overall ECERS-3 scores. Pedagogical and interactional dimensions showed limited or inconsistent relationships with structural variables. Future research should carefully consider how ECERS-3 scores are analyzed and be mindful of potential threshold effects when exploring associations with structural quality.