We test empirically how caregiver reports of DSM-IV symptoms of Attention Deficit Hyperactivity Disorder (ADHD) vary by child’s gender in a sample of 206 middle-class Mexican children, ages 6–12 years. Objective measures of children’s hyperactive and inattentive behavior, derived from ethological observation and activity monitoring, are used as a control in regression analyses. When these objective measures of behavioral differences are taken into account, teachers ascribe more inattention symptoms to boys than girls. Parents, by contrast, do not display a significant gender difference in identification of children’s ADHD symptoms. This study provides an empirical demonstration that children’s ADHD symptoms can be, but need not always be, reported differently based on cultural models expecting behavioral differences. In this case, child’s gender influences the way psychiatric symptoms are ascribed to them by some, but not all, groups of involved social actors.