It certainly is a phase. Most kids at 2 are exploring their growing independence. They're noticing they have new motor skills that allow them some freedom to explore their environment, and finding they have strong preferences but little ability to regulate their emotions. One of the reasons why we have the phrase "terrible twos" is that this is commonly when a child's capability for exploring the world is clashing with the rules of the world.

Every family with a two-year-old may experience acting out—the child doesn't want to put on his shoes, or he doesn't want to go to bed one night a week, so there's a lot of screaming. But if it's happening every morning as you go out, or the house ends up looking like a disaster area, or it happens every night for bedtime, or it takes hours to get the child to bed, and parents are pulling their hair out and no one is sleeping—that is when professional help may be necessary.

I often tell parents about a clinical acronym we use to better understand whether a child's symptoms are consistent with a mental health diagnosis: FIDI, for "Frequency, Intensity, Duration and Impairment." When parents come into the office worrying about a child's tantrums, I ask, "How often do the tantrums happen? How intense do things get? How long do these things last and how long have they been going on? How much does it get in the way of you being able to do stuff as a family?" We have diagnostic criteria for certain behavior disorders, but those criteria don't cover every behavior that could impair a child's or family's functioning. So we have to look objectively at the frequency, intensity and duration of these behaviors, and then discuss how they're impairing the child's life and family.

Impairment is the key dividing line between "typical" and clinical, and it isn't always as sharp as we would like it to be. It may be that a child has milder behavioral issues, but they are really getting in the way for a family and causing a lot of conflict between the parents. We don't only treat problem behavior if it is the most severe it can be. We treat because a family needs help.

Parents are not necessarily the cause of behavior problems, but they can be the solution. Behavior problems have many different causes. There are biological and genetic reasons why a child might have behavioral difficulties. Some children react more strongly to interruptions in daily rhythms - like overreactions to hunger or irritability related to too little sleep. Some children have real difficulties controlling emotions, difficulties that have been there since infancy as part of a reactive and highly sensitive temperament.

To be sure, there are parent-child interaction patterns that we know lead to a higher instance of behavior problems—usually the techniques we would call "harsh discipline." Parents who end up making threat after threat, who engage in physical discipline, or who frequently criticize their children often see more behavior problems.

But the issue we see most often is parents who believe their child's behavior problems must be the result of their actions or some mistake in discipline, like being too harsh or too permissive. The reality is it can happen to anybody, and we want to re-establish a balance between nurture and structure in effectively managing behavior. We see parents who have what seems to be flawless parenting strategies with one child in a family, and through no fault of their own, the other child has just stumbled upon ways of coping with stress or with their emotions that become impairing and disruptive over time. Parenting is just a part of what goes into a child's behavior patterns; but parent behavior is adjustable, so it's one of the most powerful tools we have.

There is no FDA-approved medication for oppositional defiant disorder (ODD) or conduct disorder (CD), the diagnoses that apply to this sort of behavior, but medications are sometimes used as an adjunct to behavioral therapy. Frequently, children with ODD also have a diagnosis of ADHD. Stimulant medication may be used if a child has difficulty paying attention to adults, following directions or exhibits excessive impulsivity. Antidepressants may also be helpful if a child has underlying depression or anxiety that may be contributing to irritability or problems regulating emotions.