Recent literature has emphasized the need to examine executive functions (EF) in children using multiple sources, including both parent rating and performance-based measures. Computerized Go/No-Go tests, including commercially available continuous performance tests (CPTs), represent one of the most commonly used methods of assessing inhibitory control - a variable central to the executive function construct. We examined the relationship between parent ratings of inhibitory control and CPT performance in two mixed clinical samples. Experiment 1 examined 109 children ages 6-18 using the Behavior Rating Inventory of Executive Function (BRIEF; Gioia, Isquith, Guy, & Kenworthy, 2000) and the Conners' CPT-II (Conners, 2000). In this sample, ratings on the BRIEF Inhibit scale (mean T-score = 62.3) were significantly higher than the CPT-II commissions score (mean T-score = 50.7; p < .0001); and the BRIEF and CPT-II scores were not highly correlated (r = - .12). Experiment 2 examined a sample of 131 children ages 7-18 using the BRIEF and the Tests of Variables of Attention (TOVA; Greenberg, 1996). In this sample, parent ratings on the BRIEF Inhibit scale (mean T-score = 56.8) were similar to TOVA commissions scores (mean T-score = 58.6; p = .33), although still poorly correlated (r = -.02). Factor analyses exploring covariance between BRIEF scales CPT-II variables (Experiment 1) and between BRIEF and TOVA (Experiment 2) yielded similar findings. In both experiments, all eight BRIEF scales loaded on a single factor, with no overlap with either the CPT-II or the TOVA. In mixed outpatient clinical samples, the BRIEF appears to measure different elements of inhibitory control than those assessed by computerized continuous performance tests.