For children age birth to five, physical, cognitive, linguistic, and social-emotional growth and development occur at a rapid pace. While all children in this age range may not reach developmental milestones (e.g., smiling, saying first words, taking first steps) at the same time, development that does not happen within an expected timeframe can raise concerns about developmental disorders, health conditions, or other factors that may negatively impact the child's development. Early, frequent screening of young children for healthy growth and development is recommended to help identify potential problems or areas needing further evaluation. For developmental screening to be effective, it should begin early in a child's life-be repeated throughout early childhood; and use reliable, valid screening tools appropriate to the age, culture, and language of the child. This compendium has been created to help practitioners better understand this information and make informed choices about the developmental screening tools they use with children birth to age five. It aims to: (1) discuss the purpose of developmental screening and how it differs from child assessment; (2) "translate" technical psychometric information about the reliability and validity of commonly-used developmental screening tools into language that is easily understood by early childhood practitioners; and (3) highlight areas in which the early childhood field is lacking information on reliability and validity of available developmental screening tools. (Individual sections contain references.) Two appendices are included: (1) Glossary of Terms; and (2) Psychometric Documentation and Rationale.