In the present study the longitudinal relations between quantity of centre-based child care (in months) and teacher reports of internalising and externalising behaviour in the first and second grades were examined for 325 Slovenian children. The socio-political context of affordable, accessible and homogenously high-quality child care is quite different compared to the context in countries from which many child-care studies originate (e.g. the USA). In Slovenia quality standards are regulated (child:staff ratio, teacher education, curriculum), the service is subsidised and children are guaranteed a place after the end of parental leave (i.e. at 11 months). In the described socio-political context a beneficial effect of child care quantity was found for internalising behaviour, while there were negative effects for externalising behaviour. Children who spent more time in child care exhibited less internalising behaviour and more externalising behaviour in the first grade of school, both with small coefficient sizes. Our study shows that even in the context of progressive child care some positive as well as less positive effects of child care participation on child development occur. (author abstract)