Critical thinking (CT) has been of longstanding interest among scholars, educators, and others who are concerned with thinking skills. The Watson-Glaser Critical Thinking Appraisal (WGCTA) is the oldest and among the most widely used and studied CT measure. It was constructed around five subscales (or CT skills): inference, recognition of assumptions, deduction, interpretation, and evaluation of arguments. This paper describes a two part analysis of the psychometric properties of the WGCTA, based on 13 sets of subscale inter-correlations and 60 sets of subscale means retrieved from published studies. We performed a meta-analysis on the inter-correlations of the 10 combinations of subscales and found that all of the average correlations that resulted were significant, but that all but one was significantly heterogeneous. Subsequently, we conducted principal components analysis on 60 subscale means of two different versions of the WGCTA. Each produced a one-factor solution, accounting for 82.69% and 79.55% of the total variance, respectively. Together these two parts of this study suggest that the WGCTA should be viewed as a measure of general competency, and that the subscales should not be interpreted individually.