By Jessica Lentz, LBA, BCBA — Clinical Director, Sunshine Advantage Clinically reviewed by Shani Slater, LBA, BCBA
Last updated: May 28, 2026
Children do not have tantrums to be “bad” — they have tantrums because they are trying to communicate something they do not have the words for yet. ABA therapy uses a method called Functional Communication Training (FCT) to teach your child a faster, easier way to ask for what they need — with spoken words, signs, picture cards, or a speech-generating device. Once the new way works, the tantrums fade because they are no longer necessary.
Most parents arrive in ABA therapy thinking of tantrums, aggression, and self-injury as behavior problems. They are not wrong. But the framing matters, because the lens you use to look at a behavior determines the strategy you try.
In our ABA therapy practice, we look at challenging behavior through a different lens. Most of the time, the behavior is communication. The child is telling us something — sometimes loudly, sometimes desperately, sometimes in ways that put them or others at risk. The behavior is not the problem. The behavior is the only tool the child currently has for solving a problem.
Once you see this clearly, the solution is obvious: give the child a better tool.
This is Functional Communication Training. It is one of the most studied, most effective, most widely used interventions in modern ABA therapy. And it works.
Functional Communication Training was first formally described in a landmark 1985 paper by Edward Carr and V. Mark Durand, Reducing behavior problems through functional communication training, published in the Journal of Applied Behavior Analysis. Carr and Durand demonstrated, with a small group of children with developmental disabilities, that severe problem behavior could be substantially reduced — not by punishing the behavior, but by teaching a functionally equivalent communication response that produced the same reinforcer.
In the decades since, FCT has accumulated one of the strongest evidence bases of any behavioral intervention. The Council of Autism Service Providers and the National Standards Project both include FCT among the established, evidence-based practices for children with autism.
A well-implemented Functional Communication Training program in ABA therapy follows five steps.
Before we teach a new communication response, we must know what the child is communicating now. This starts with identifying the function of the behavior — figuring out whether the behavior is maintained by attention, escape, tangible, or sensory reinforcement.
This step cannot be skipped. The replacement behavior must produce the same reinforcer the problem behavior has been producing. Otherwise the child will keep using the old behavior, because it still works.
The FCR is the new behavior the child will use instead of the problem behavior. The choice depends on the child’s communication skills and motor abilities. Common FCRs include:
The FCR should be (1) easier to perform than the problem behavior, (2) more efficient at producing the reinforcer, and (3) likely to be recognized by adults in the child’s environment.
A child who has spent two years learning that biting gets them a break does not need a complex four-word sentence as the replacement. They need a single sign or card that works every time, instantly.
We teach the FCR in conditions that closely match when the problem behavior typically occurs. If the child usually hits during clean-up demands, we teach the “break” sign or card during clean-up — at the very first sign of frustration, prompted heavily, and reinforced immediately with a real break.
The teaching is usually prompt-heavy at first. We do not wait for the child to spontaneously use the new response. We prompt it, reinforce it, and gradually fade the prompt.
This is the part where the magic happens. The new FCR is reinforced consistently — every single time the child uses it. The old problem behavior is put on extinction — it no longer produces the reinforcer.
The child quickly learns: the sign for “break” works, screaming doesn’t. The new behavior is faster, less effortful, and more reliable. So the child uses it more, and the old one fades.
This is also where the extinction burst we wrote about elsewhere may show up. Plan for it.
Once the FCR is reliable, we begin to teach the child to tolerate delay. In the real world, no one gets every request granted instantly. We thin the schedule of reinforcement — from “every time you sign ‘break,’ you get a break immediately,” to “every time you sign ‘break,’ you wait ten seconds, then twenty, then sixty.” We add visual timers, “first/then” boards, and tolerance training.
Schedule thinning is the difference between a child who uses FCT in clinic and a child who can use it in the grocery store, at grandma’s house, and at school. For many families, in-home ABA therapy is where this generalization starts because the therapist can coach communication during real routines like cleanup, meals, transitions, and bedtime.
We will call her L. L. was four when she came to us, which is a common age when families begin looking for a structured ABA preschool program or clinic-based support. Her parents had tried everything — time-outs, sticker charts, taking away the iPad. Nothing worked, and most things made it worse.
Our FBA showed that L.’s biting was almost entirely escape-maintained — biting got her out of any non-preferred demand within seconds. Her language was limited to about a dozen single-word tacts. She had no functional mands.
We selected a single picture card — a square with the word “BREAK” — as the FCR. For two weeks, every time we saw the smallest sign of frustration (clenched fists, body stiffening, the precursor to a bite), we prompted L. to hand us the card. The instant the card touched our hand, we said “break!” and gave her thirty seconds away from the demand. We did this dozens of times a day.
Within ten days, L. handed us the card without prompting. Within three weeks, biting had dropped to two or three episodes a week — and those episodes were nearly always when we had failed to honor a “break” card quickly enough.
L. is now six. She uses the card for “break,” and she uses a speech-generating device for about thirty other mands. She bites perhaps twice a year, almost always when ill.
This is what FCT does. It does not “stop tantrums.” It gives the child a better tantrum — one that does not hurt anyone and is socially acceptable in any setting.
“What if I don’t honor the request?” Honoring the FCR consistently in the early days is non-negotiable. Once the FCR is established, schedule thinning teaches the child to wait — but in the early phase, every request gets honored. Honor matters more than convenience.
“What if my child starts using the FCR all day?” This is a good problem. We address it with schedule thinning, choice cards, and clear “first/then” boundaries. We never punish a child for using the new communication response — that destroys the FCR and brings back the old behavior.
“What if the FCR doesn’t fit at school?” A picture card system fits anywhere. Sign language fits anywhere. A speech-generating device fits anywhere. Part of the BCBA’s job is to ensure the FCR works across environments — and to train teachers, grandparents, and siblings to honor it.
FCT is most powerful when:
FCT is not the right primary intervention for every behavior. Automatic/sensory-maintained behaviors are usually treated with different procedures. Multiply maintained behaviors may need a layered approach.
During the ABA therapy assessment process, your child’s BCBA can tell you whether FCT is right for the behavior you are most concerned about.
FCT is an evidence-based ABA therapy procedure that teaches a child a new communication response (spoken, signed, picture-based, or device-based) that produces the same reinforcer as a challenging behavior. The new response replaces the challenging behavior because it is faster and more reliable.
FCT reduces challenging behaviors substantially in the majority of cases when it is implemented correctly. It works best when the function is identified, the FCR is well-chosen, and the new response is honored consistently in the early phase.
No. The FCR is whatever fits the child’s current skills. As language develops, many children transition from picture cards to spoken language. The goal is functional communication, not a specific modality.
Yes. Even verbal children sometimes lack the functional language for specific situations — like requesting a break or expressing pain. FCT can teach these specific functional responses regardless of overall language level.
This concern comes up often, and the research is clear: providing a communication device does not slow speech development. In many cases it accelerates it, because the child finally has a reliable way to get their needs met and is freed to focus on other learning.
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