ADHD in girls, more commonly, is the inattentive type, that is without the hyperactivity part. In boys, it is more common the combined type, ADHD with hyperactivity. However, you can have it the other way around. You can have girls who are hyperactive and boys that are predominantly inattentive. More often in girls, you find the quiet, daydreamy, non-disruptive form. That's why girls don't get diagnosed, because they aren't causing anyone any problem. They are dismissed as slow or shy or not very bright. The boy has to get diagnosed because he is overturning the desks. You want to keep your eye out for the inattentive type of ADHD, more commonly in girls than in boys. Those are the ones who get overlooked. Any child who is underachieving and you don't understand why, consider that they may have ADHD.