How a Functional Behaviour Assessment (FBA) Works: A Parent-Friendly Guide

When I first learned about FBAs during my behaviour-analysis training, I assumed they were something discussed mainly by psychologists and specialist teams. In practice, many parents come across the term when they are looking for help understanding why a child’s behaviour keeps happening—often after familiar advice has not changed the situation.

If you’re reading this because you’re trying to understand why your child’s behaviour keeps happening, this guide explains what an FBA is, how the process works, what its limits are and what you can safely observe at home to support a professional assessment.

If you are trying to decide whether a repeated behaviour needs more structured support, the free 25-minute Behaviour Clarity Session can help you describe one situation clearly and decide what information may matter next. It is not an FBA, a diagnosis or a confirmed functional conclusion.

Check suitability and choose a time

What Is a Functional Behaviour Assessment (FBA)?

An FBA is a structured process for developing and testing hypotheses about the relationships between a behaviour and the context in which it occurs. It should not begin with a label or assume that one explanation fits every situation.

Depending on the person’s needs and the level of risk, the process may include:

  • a clear, observable description of the behaviour, including its frequency, duration, intensity and impact
  • the events, times and situations that predict when the behaviour does and does not occur across everyday routines and settings
  • what happens immediately afterwards, including consequences that may influence whether the behaviour happens again
  • relevant health, communication, sensory, developmental, social and environmental factors
  • direct observations, baseline measurements, interviews and reviews of existing records

The outcome is usually one or more working hypotheses describing possible relationships between triggers, behaviour and what follows. Those hypotheses should remain open to revision when new information appears.

FBA looks for patterns that may help explain what a behaviour achieves or communicates in a particular context. It does not turn a few observations into certainty.

A functional analysis is a more specific assessment method in which conditions are systematically changed to test a possible functional relationship. It requires appropriate competence, planning and safeguards. Not every FBA needs the same level of assessment; the process should be phased and proportionate to the complexity and risk involved.

Common Behavioural Functions (in Plain English)

Practitioners often group maintaining consequences into broad categories, but a good FBA should not force every pattern into a simple box.

  1. Social positive reinforcement: the behaviour may bring attention, help, closeness, an item or access to an activity.
  2. Social negative reinforcement: the behaviour may delay, reduce or help the person get away from a task, situation, interaction or other demand.
  3. Automatic reinforcement: the behaviour may produce an effect directly, such as sensory stimulation or relief, without depending on another person’s response.

A behaviour can have more than one function, and some maintaining variables are highly individual. Sensory differences may affect when behaviour is more likely, but that does not automatically mean the behaviour is maintained by automatic reinforcement.

Communication difficulties are not a separate behavioural function. They may make it harder for a child to obtain help, request a break, gain access or communicate discomfort safely. That can point towards an important replacement skill, but the assessment still needs to identify what changes when the behaviour occurs.

These are descriptions of behaviour–environment relationships, not labels for your child.

What a Good FBA Looks Like (and What to Watch Out For)

A formal FBA should be led by someone with relevant competence and experience. NICE guideline NG11 applies specifically to children, young people and adults with a learning disability whose behaviour challenges. Within that scope, it recommends keeping the person at the centre, involving family members and carers, considering personal and environmental factors, and making the depth of assessment proportionate to the severity and complexity of the behaviour.

A good FBA may include:

  • the child’s perspective where possible, alongside input from parents, carers, school staff and other relevant people
  • a precise definition of the behaviour that different people can recognise and record consistently
  • direct observation across the routines and settings in which the behaviour is most and least likely
  • baseline information about frequency, duration, intensity, risk and quality-of-life impact
  • consideration of health, medication, sleep, communication, sensory needs, trauma history, recent changes and the wider environment
  • working hypotheses that clearly separate what was observed, what was reported, what may be relevant and what remains unknown
  • a support plan linked to the assessment, with agreed outcomes and measures for reviewing whether it is helping

A weak assessment often looks like:

  • a tick-box exercise with no clear behavioural description or direct data
  • a function assigned from one incident, one questionnaire or a broad label
  • little or no involvement from the child, family or people who know the everyday context
  • a hypothesis presented as proven fact without showing the evidence or uncertainty
  • generic advice that is not logically connected to the assessment findings

A statement such as “we think it is attention-seeking” is not enough. A useful hypothesis should describe the context, the behaviour, what follows and the evidence supporting that relationship.

Your Role as a Parent (and Why You’re Not Expected to Do the FBA Yourself)

Parents often carry detailed knowledge that a short appointment cannot capture: what happens before and after the behaviour, which routines are difficult, what has changed recently and what helps their child feel safe and understood. That contribution matters, but it does not mean you should be expected to conduct a formal FBA by yourself.

A professional should bring the technical assessment skills. You bring knowledge of your child’s everyday life. The strongest process combines both and includes your child’s views wherever possible.

If the concern is happening at school in England, start with the class teacher and the school’s special educational needs coordinator (SENCO). Ask how the behaviour is being defined, what has been observed, what support is being tried and how it will be reviewed. This fits the graduated assess–plan–do–review approach used in SEND support.

You can also ask who is responsible for the assessment, what evidence supports the current hypothesis, how health and communication needs have been considered, and when the plan will be reviewed. Asking for clarity is not the same as blaming anyone.

What You Can Do at Home: Safe & Meaningful Observations

You can collect useful observations without trying to prove a function or recreate a difficult situation.

1. Notice what happened just before

Was there a transition, noise, instruction, delay, change in routine, difficult task, discomfort or loss of access to something important?

2. Describe the behaviour neutrally

Write what someone could see or hear. For example: “At 3:05 pm, when the teacher said ‘time to stop playing’, my child dropped the tray and walked away,” rather than “He had a tantrum.”

3. Notice what happened immediately afterwards

Did someone move closer, speak, help, pause a task, change the environment or provide access to something? Record what happened without assuming it caused the behaviour.

4. Include the wider context

Note anything that may have affected the situation, such as sleep, pain, illness, hunger, medication changes, sensory load, communication difficulties or an unusual event.

5. Look for patterns—and exceptions

One incident rarely tells the whole story. Record when the behaviour occurs, when it does not occur and what is different across those situations.

Keep observations separate from interpretations. “The demand stopped for five minutes” is an observation; “the behaviour was definitely escape-maintained” is a hypothesis that needs further assessment.

What You Should Not Do

Because ethics, dignity and safety come first:

  • Do not deliberately trigger the behaviour or change conditions to “test” an idea unless this is being led by a suitably competent professional with appropriate safeguards.
  • Do not assume an ABC record, checklist or single incident proves the function. These tools can help identify patterns, but the conclusion remains a working hypothesis.
  • Do not withhold comfort, communication support or reasonable adjustments as an experiment.
  • Do not build a behaviour support plan around a guessed function. A mismatched strategy can be ineffective and may increase distress or risk.
  • Do not overlook possible pain, illness or another sudden change in health. Seek appropriate medical advice when this may be relevant.

If there is immediate danger, prioritise safety and contact the appropriate emergency or urgent support service. A blog article or short consultation is not a substitute for an individual risk assessment.

How an FBA Can Help

When an FBA is conducted carefully and the findings are used well, it can help the people around a child respond more consistently and choose support that matches the context. It may contribute to:

  • a shared, observable description of the behaviour across home and school
  • greater clarity about patterns, triggers and maintaining consequences
  • support for communication, coping and other replacement skills linked to the working hypothesis
  • changes to routines or environments that reduce unnecessary distress and risk
  • clear measures for checking whether the plan is helping the child’s safety, participation and quality of life

An FBA does not guarantee a simple answer. Data may be inconsistent, several variables may be involved and a hypothesis may need to change. That is not failure; it is part of a careful assessment process.

Reassurance and Next Steps

If things feel hard, it may help to remember that behaviour is not a character verdict on your child or on you. The aim is to understand what is happening well enough to improve safety, dignity, participation and quality of life.

You do not need to arrive with the answer. Bring concrete examples, note what you have observed and ask the team to explain how its conclusions connect to the evidence.

“Can we define the behaviour clearly, review what happens before and after it, and agree what information we need next?”

A useful plan is collaborative, transparent about uncertainty and reviewed against what actually changes for the child.

General information can only take you so far. If you are unsure how to describe the pattern or what support to ask for, the free 25-minute Behaviour Clarity Session gives you space to talk through one repeated situation and check whether the session is suitable. It does not provide an FBA, a confirmed function or a behaviour support plan.

Check suitability and choose a time

References

Hanley, G. P. (2012). Functional assessment of problem behavior: Dispelling myths, overcoming implementation obstacles, and developing new lore. Behavior Analysis in Practice, 5(1), 54–72.

O’Neill, R. E., Albin, R. W., Storey, K., & Sprague, J. R. (2015). Functional assessment and program development for problem behavior (3rd ed.). Cengage Learning.

National Institute for Health and Care Excellence. (2015). Challenging behaviour and learning disabilities: Prevention and interventions for people with learning disabilities whose behaviour challenges (NG11).

Gore, N. J., McGill, P., Toogood, S., Allen, D., Hughes, J. C., Baker, P., & Denne, L. D. (2013). Definition and scope for positive behavioural support. International Journal of Positive Behavioural Support, 3(2), 14–23.

Dunlap, G., & Fox, L. (2009). Parent-professional partnerships in early intervention. Infants & Young Children, 22(1), 3–17.

Beavers, G. A., Iwata, B. A., & Lerman, D. C. (2013). Thirty years of research on the functional analysis of problem behavior. Journal of Applied Behavior Analysis, 46(1), 1–21.

Department for Education & Department of Health. (2015). SEND code of practice: 0 to 25 years.