Recent concern about malingered self-report of symptoms of attention-deficit hyperactivity disorder (ADHD) in college students has resulted in an urgent need for scales that can detect feigning of this disorder. The present study provided further validation data for a recently developed validity scale for the Conners’ Adult ADHD Rating Scale (CAARS), the CAARS Infrequency Index (CII), as well as for the Inconsistency Index (INC). The sample included 139 undergraduate students: 21 individuals with diagnoses of ADHD, 29 individuals responding honestly, 54 individuals responding randomly (full or half), and 35 individuals instructed to feign. Overall, the INC showed moderate sensitivity to random responding (.44–.63) and fairly high specificity to ADHD (.86–.91). The CII demonstrated modest sensitivity to feigning (.31–.46) and excellent specificity to ADHD (.91–.95). Sequential application of validity scales had correct classification rates of honest (93.1%), ADHD (81.0%), feigning (57.1%), half random (42.3%), and full random (92.9%). The present study suggests that the CII is modestly sensitive (true positive rate) to feigned ADHD symptoms, and highly specific (true negative rate) to ADHD. Additionally, this study highlights the utility of applying the CAARS validity scales in a sequential manner for identifying feigning.