Objective: Little empirical attention has been paid to the validity scales of the Trauma Symptom Checklist for Children (TSCC). The purpose of this study is to examine the prevalence of cases identified by the validity scales and its analytical impact. Methods: The current study compares regression models using data from two community samples (n = 3,724 and n = 2,245) and two samples of at-risk youth (n = 1,758 and n = 204). Using Chow tests to compare coefficients, we demonstrate the implications of removing cases identified by the TSCC validity scales. Results: The Underresponse (UND) scale identified 8% of the community sample and 20% of the at-risk sample. Chow tests revealed significant group differences based on the UND scale for all TSCC subscales. Conclusion: The present study demonstrates the analytical impact of the TSCC validity scales and provides statistical evidence for the removal of invalid cases.