Based on the knowledge that direct assessment of the quality of early childhood educational environments is becoming more and more important, this article deals with a coordinated adaptation of the Early Childhood Environment Rating Scale (ECERS) in Germany and Portugal. The ECERS, developed by Harms and Clifford (1980), is a complex rating scale, comprising 37 items, which is implemented to assess major quality characteristics of early childhood classrooms and has been used quite extensively in the US as well as in other countries. In this article we describe how the scale was adapted and we report selected results of a jointly coordinated comparative study on a sample of 103 early childhood classrooms in Germany and 88 in Portugal. The classrooms were classified according to three different types in each country. In particular, we report the item characteristics of the adapted versions, reliabilities and intercorrelations of the total scale and the apriori-subscales, and results of factor analyses. A one-way ANOVA indicates group differences between the six types of classrooms which can be meaningfully interpreted.