Quality measures were originally developed for research aimed at describing the settings that children spend time in and identifying the characteristics of these environments that contribute to children's development. They were also developed to guide improvements in practice. Increasingly, however, measures of quality are being used for further purposes. In particular, they are being used to guide components of state policies. For example, many states are developing Quality Initiatives and employing measures originally created for research or for guiding improvement in practice for the new purpose of assigning quality ratings to early care and education settings. States are also using these measures to monitor change in quality over time. This publication is being compiled by Child Trends for the Office of Planning, Research and Evaluation of the Administration for Children and Families, U.S. Department of Health and Human Services, to provide a consistent framework with which to review the existing measures of the quality of early care and education settings. Its aim is to provide uniform information about quality measures. It is hoped that such information will be useful to researchers, practitioners, and in informing the measurement of quality for policy-related purposes. Individual profiles contain figures, references, tables, and footnotes. [This paper was prepared for the Office of Planning, Research and Evaluation, Administration for Children and Families, U.S. Department of Health and Human Services.]