This study examines the effects of teachers' speech and hand gestures on the task performances of students with Attention-Deficit/Hyperactivity Disorder (ADHD). Forty-five 7 1/2-year-old students clinically diagnosed with ADHD participated in the study. The students were asked to solve three sets of puzzles. The teachers supported the students in the tasks by using three different scaffolding modalities: speech-only, gesture-only and speech in conjunction with gestures. The results indicate that when the teachers used the scaffolding that contained gesture components (either speech scaffolding in conjunction with gesture scaffolding or gesture-only scaffolding), the ADHD students were more responsive, focused longer on the tasks and were more successful in completing the tasks. Moreover, teachers' representational and deictic gestures were found to be the most effective gestures in scaffolding. This study suggests that when teachers' hand gestures are used together with speech, they are a powerful pedagogical means to engage ADHD children in tasks.