Cognitive Behavioral Therapy (CBT) and Rational Emotive Behavior Therapy (REBT) are evidenced-based approaches that have been identified as effective for the treatment of psychological disorders among youth (Bernard & Terjesen, 2020). However, although beliefs and cognitions have been shown to be predictive of emotional and behavioral problems in children (Mogoaşe, Podină, et al., 2013), and modifications in cognitions have been shown to be vital for treatment (David et al., 2017), the research and psychometric properties surrounding measures designed to specifically assess irrational beliefs, self-statements, or automatic thoughts in youth are lacking due to theoretical and practical limitations (Terjesen et al., 2020). The aim of the present study was to address the aforementioned concerns in the measurement research by validating a new self-report measure of irrational beliefs designed for children ages 8 to 11 years old which assesses multidimensional responses to different realistic situational vignettes and is based on the REBT conceptualization of irrationality: The Children’s Irrational Response Checklist (CIRCL). Results showed partial support of the proposed hypotheses within one of the three sample groups including adequate predictive, convergent, and discriminant validity as well as moderate to strong correlates between the CIRCL and other established measures of beliefs (e.g., Child and Adolescent Scale of Irrationality [CASI], Children's Automatic Thoughts Scale [CATS]) and social-emotional functioning (Behavior Assessment System for Children, Third Edition [BASC-3]). These preliminary results add to the limited research within this area, provide promising areas for future research, and have important clinical implications for assessing and treating irrationality among youth.