Background: Both performance-based and rating measures are commonly used to index executive function in clinical and neuropsychological assessments. They are intended to index the same broad underlying mental construct of executive function. The association between these two types of measures was investigated in the current article. Method and Results: We examined the association between performance-based and rating measures of executive function in 20 studies. These studies included 13 child and 7 adult samples, which were derived from 7 clinical, 2 nonclinical, and 11 combined clinical and nonclinical samples. Only 68 (24%) of the 286 relevant correlations reported in these studies were statistically significant, and the overall median correlation was only 0.19. Conclusions: It was concluded that performance-based and rating measures of executive function assess different underlying mental constructs. We discuss how these two types of measures appear to capture different levels of cognition, namely, the efficiency of cognitive abilities and success in goal pursuit. Clinical implications of using performance-based and rating measures of executive function are discussed, including the use of these measures in assessing ADHD. (Contains 2 tables and 2 footnotes.)