Few studies of measures or techniques designed to detect feigning of Attention-Deficit/Hyperactivity Disorder (ADHD) have included groups reporting symptoms of depression and anxiety. Based on the high rate of comorbidity between ADHD and mood disorders, inclusion of such groups is important to mimic clinical referral patterns. The current study evaluated the validity of the ADHD Symptom Infrequency Scale (ASIS), a measure designed to detect malingered symptoms of ADHD, in a four-known groups design that included a group consisting of subjects with symptoms of anxiety and depression. Four groups were included in the current study: (1) control, (2) simulator, (3) ADHD diagnosed, (4) individuals with elevated symptoms of depression/anxiety. The ASIS Infrequency scale showed strong internal consistency (