Abstract
This article addresses the following cross-cutting issues evident in the special section of this issue: (a) current diagnoses do not provide adequate validity criteria; (b) the heterogeneity and comorbidity of target problems raise taxonomic challenges; (c) accurate assessment requires integration of multisource data; (d) developmental variations must be accommodated; (e) appropriate norms are needed; and (f) categorical and quantitative approaches are not incompatible. Less evident in the special section articles but equally important are the need to cope with multicultural issues, avoid premature closure regarding diagnostic labels, assess caregivers, and standardize broad-spectrum assessment procedures. Studies and use of evidence-based treatment (EBT) should be linked to evidence-based assessment (EBA) to advance both EBT and EBA.