All children can exhibit inattention or be fidgety or impulsive from time to time. How can you tell if your child’s behavior is within the normal range or whether he or she might have attention deficit hyperactivity disorder, or ADHD? “It’s tricky — as parents, you don’t want to assume,” says Betsy Davenport, PhD, a clinical psychologist who specializes in ADHD and is in private practice in Portland, Ore. “It could be nothing. On the other hand, it could be way, way serious.”

“In general, it has to do with age and stage,” says Dr. Davenport. “Does your child behave like other kids his age?” For example, if your child hasn’t learned to sit still when all her friends have, it’s a sign that something may be up, Davenport says.

Frequency, intensity, and duration also are clues. Children with ADHD show at least one, and sometimes all, of the three major ADHD symptoms: hyperactivity, impulsiveness, and inattention. And they show them more often and more strongly than other children their age or who are at the same developmental level. A child with ADHD will exhibit signs no matter the setting — the behavior is the same at home and at school. And the behavior will occur consistently over a long period of time.