High amounts of early child care have sometimes been linked to higher levels of behaviour problems, while high-quality child care has more often been related to fewer behaviour problems and more social competence. The current study investigated whether the level of centre emotional and behavioural support (child care quality) interacted with the amount of child care in predicting children's socio-emotional behaviour. Participants were 417 children (mean age = 27 months) from 61 Dutch daycare centres. The amount of daycare ranged from 1 to 5 days per week (M = 2.3 days). Multi-level analyses showed that, independent of the amount of daycare, high levels of centre emotional and behavioural support were related to more caregiver-rated social competence 1 year later. In addition, children spending 3.5 days or more in highly supportive daycare centres showed the lowest levels of parent-rated externalizing behaviour 1 year later. The findings emphasize (a) that the combined effects of the amount and quality of child care are important and (b) that high-quality early child care is related to children's socio-emotional development. Further policy, practice, and research implications are discussed. Highlights: We studied in a Dutch sample how the amount and quality of daycare interacted in relation to children's socio-emotional outcomes. High levels of daycare quality were related to more teacher-rated social competence. Children spending 3.5 days or more in highly supportive daycare centers showed less parent-rated externalizing behavior.