In Brief Critical appraisal is the assessment of research studies' worth to clinical practice. Critical appraisal—the heart of evidence-based practice—involves four phases: rapid critical appraisal, evaluation, synthesis, and recommendation. This article reviews each phase and provides examples, tips, and caveats to help evidence appraisers successfully determine what is known about a clinical issue. Patient outcomes are improved when clinicians apply a body of evidence to daily practice. How do nurses assess the quality of clinical research? This article outlines a stepwise approach to critical appraisal of research studies' worth to clinical practice: rapid critical appraisal, evaluation, synthesis, and recommendation. When critical care nurses apply a body of valid, reliable, and applicable evidence to daily practice, patient outcomes are improved.