The purpose of this study was to investigate the relationship between two structural factors of quality: organisation form (stable groups versus flexible groups) and staff-child ratio, in relation to interaction quality in toddler groups in Norwegian early childhood education and care (ECEC). Data were collected from 206 kindergarten groups in the period from 2013 to 2015. Interaction quality was measured through the infant/toddler environment rating scale-revised subscales, Interaction, listening and talking, and program structure. A two-way MANOVA revealed that organisation form with small, stable groups were related to higher interaction quality, while the staff-child ratio and interaction quality varied depending on different content dimensions. These findings have clear implications for policy and the training of ECEC staff. (author abstract)