The effectiveness of surgical interventions can be recognized through the careful selection and measurement of appropriate outcomes. Ideally, studies investigating the same surgical intervention should report the same outcomes. Consistent reporting permits the pooling of data and the development of systematic reviews and meta-analyses, which can provide the highest level of evidence for informing clinical practice. Core Outcome Sets (COS) are standardized sets of outcomes that should be measured and reported in all clinical trials relating to a health condition of interest. Many surgical specialties are introducing COS for various conditions, yet there is little direction given to surgeons on how to effectively apply COS to their research. Using a clinical scenario, this chapter provides a guideline that surgeons and researchers can follow to appraise and apply a COS in their research. A published COS is reviewed and appraised using predetermined appraisal questions. The process of answering these questions, along with examples from the literature, will ensure that readers are more confident in their ability to appraise a COS, ensuring appropriateness and methodological rigor prior to application.