In nursing, diagnostic testing is commonly a regulated activity performed by nurse practitioners and midwives. However, assessment and screening of patients for further testing (case finding) are central elements of nursing. The number of studies evaluating assessments and tests is increasing, but overall, the methodological quality of these studies has been poor.¹ Thus, nurses should be able to critically appraise evidence from such studies to ensure that the highest quality assessment and screening tools are used. The tools of assessment, case finding (or screening), and diagnosis are evaluated using different criteria from those applied to studies investigating preventive or therapeutic interventions, although the 3 basic questions of critical appraisal are the same: are the results valid? What are the results? Will the results help me in caring for my patients? In this article, we outline a framework by Sackett et al² to critique studies that evaluate a screening tool to assess patients for depression. The same framework can also be applied to studies of assessment tools such as fall risk assessments or pressure sore risk scoring, as well as studies of diagnostic tests.