The main purpose of this article and this special section is to encourage greater attention to evidence-based assessment (EBA) in the development of a scientifically supported clinical child and adolescent psychology. This increased attention is especially important in light of (a) the omission of assessment considerations in recent efforts to promote evidence-based treatments for children and (b) ongoing changes in the nature of clinical child assessment. We discuss several key considerations in the development of guidelines for EBA, including the purposes of assessment, the role of disorder or problem specificity, the scope of assessment, assessment process parameters, possible "cross-cutting" assessment issues, psychometric considerations, and issues related to the clinician's integration of assessment data. We conclude the article with suggestions for how current, summary information on EBA can be developed, maintained, and disseminated.