An important research question is whether Attention Deficit Hyperactivity Disorder (ADHD) is related to early- or late-stage attentional control mechanisms and whether this differentiates a nonhyperactive subtype (ADD). This question was addressed in a sample of 145 ADD/ADHD and typically developing comparison adolescents (aged 13-17). Attentional blink and antisaccade tasks were used to assay early- and late-stage control, respectively. ADD was defined using normative cutoffs to ensure low activity level in children who otherwise met full criteria for ADHD. The ADD group had an attenuated attentional blink versus controls and ADHD-combined. The effect was not produced using "DSM-IV" definition of ADHD-primarily inattentive type or "DSM" symptom counts. ADHD-combined showed greater weakness in response inhibition, as manifest in the antisaccade task. Combining tasks yielded an interaction differentiating group performance on the two tasks. (Contains 4 tables and 4 figures.)