This chapter considers the clinical utility of science- and evidence-based clinical assessment. Clinical utility is a complex, multi-faceted, higher-order construct defined as the degree to which the data from an assessment instrument assist the clinician in making judgments about a client, enhance the validity of those judgments, or improve upon the costs and benefits associated with acquiring those data. Validity is often confused with utility and is a necessary, but insufficient, element of clinical utility of any measure that is used for screening, diagnosis, case formulation, or treatment outcome evaluation. The chapter reviews several strategies for gathering evidence of the clinical utility of assessment strategies and data from clients and clinicians. The evaluation of the clinical utility of an assessment strategy and its resultant data includes dimensions of effectiveness, cost-benefits, and feasibility. Clinical utility evaluations must be evidence-based and clinicians’ beliefs about the clinical value of an instrument are no substitute for strong evidence that the assessment data enhance clinical effectiveness. In evaluating clinical utility of an assessment strategy, instrument, or data, it is important to ascertain if it is effective in clinical practice, the value of the outcomes relative to the costs in clinical practice, and its feasibility in clinical practice. The chapter ends with recommendations for evaluating the clinical utility of assessment strategies and their resultant data.