We conducted two empirical studies to (1) explore the dimensionality of the Behavior Rating Inventory of Executive Function-2 (BRIEF-2) parent and teacher forms, (2) examine the association between the parent and teacher reports, and (3) analyze the relationship between the BRIEF-2 ratings and performance-based measures of executive functions (EFs) (including working memory, inhibition, and shifting tasks) and academic achievement in children. In Study 1 ( = 212 parents;  = 111 teachers), confirmatory factor analysis (CFA) showed that a three-factor solution that included the indices of (1) behavior regulation, (2) emotion regulation, and (3) cognitive regulation best fit the data. In Study 2 ( = 275 8- to 12-year-old Spanish-speaking children), selective and low correlations were found between performance- and rater-based measures of EFs. In addition, low to moderate correlations were found between parent and teacher reports. However, the three indices of both forms of the BRIEF-2 were associated with the diverse academic domains analyzed, although differences emerged depending on the informant (teacher vs. parent). Our results support the hypothesis that the two EF measures document different underlying processes. The clinical and educational implications of considering both perspectives in the assessment of EFs in children with typical development and in children with neurodevelopmental disorders are discussed.