The concept of validity has been a central component in critical appraisal exercises evaluating the methodological quality of quantitative studies. Reactions by qualitative researchers have been mixed in relation to whether or not validity should be applied to qualitative research and if so, what criteria should be used to distinguish high-quality articles from others. We compared three online critical appraisal instruments' ability to facilitate an assessment of validity. Many reviewers have used the critical appraisal skills program (CASP) tool to complete their critical appraisal exercise; however, CASP appears to be less sensitive to aspects of validity than the evaluation tool for qualitative studies (ETQS) and the Joanna Briggs Institute (JBI) tool. The ETQS provides detailed instructions on how to interpret criteria; however, it is the JBI tool, with its focus on congruity, that appears to be the most coherent.