This research report explores the extent to which the Early Childhood Environment Rating Scale (ECERS) (Harms and Clifford, 1980) remains a valid instrument when used to make cross-national comparisons of quality, and the advantages and disadvantages of using ECERS for this purpose. ECERS was developed to be used by a trained observer to rate the quality of early childhood settings. The majority of studies using this rating scale have been carried out in North America by American investigators, but ECERS is now beginning to be used by researchers in other countries. Some researchers have expressed reservations about its appropriateness for early childhood settings which are different from the settings for which it was developed. In this study, ECERS was used as part of a qualitative investigation into nursery provision and practice between 1990 and 1994 in four countries: the United States (New York City), Spain (Barcelona), Italy (Arezzo), and Sweden (Harnosand). Major findings include: large variability in ratings and lower mean scores (4.3) achieved by programs in New York; uniformly high ratings of programs in Sweden (6.9); and mean scores of 5.4 (Spain) and 6 (Italy) for ratings of centers. Problems identified in using ECERS included the meaning of particular items on the scale, minimal standards, and omission of items and whole dimensions of experience. Advantages of using ECERS included the short time span for administering the scale and its ability to provide comparison measures on a number of criteria which child care professionals have agreed are significant. Limitations include unstated theoretical assumptions, a failure to differentiate among high quality programs, the omission of items that assess some aspects of programs, and the need for not only the child's experience but also the experience of workers and parents (and other stakeholders) to be taken into account when assessing quality. (DR)