A functional behaviour assessment (FBA) is the structured process a behaviour support practitioner uses to work out why a behaviour of concern happens — what purpose, or function, it serves for the person. Under the NDIS, this understanding is the foundation of every comprehensive behaviour support plan: strategies only work when they address the need the behaviour is meeting, rather than the behaviour on its surface.
Key takeaways
- A functional behaviour assessment identifies the function — the purpose — of a behaviour of concern, not just its form.
- Behaviours of concern usually meet a genuine need: to get something, to escape or avoid something, or for sensory reasons.
- The FBA is the evidence base for a comprehensive behaviour support plan; the NDIS Commission treats it as the foundation for the plan's strategies.
- Only an NDIS behaviour support practitioner considered suitable by the NDIS Quality and Safeguards Commission can conduct an FBA and write the plan.
- The aim is proactive, skill-building support that meets the underlying need — reducing reliance on restrictive practices, not managing behaviour through control.
What is a functional behaviour assessment?
A functional behaviour assessment is a systematic way of understanding a behaviour of concern in the context of the person's life. Rather than asking only "how do we stop this behaviour?", it asks "what is this behaviour achieving for the person, and what unmet need does it point to?"
The NDIS Quality and Safeguards Commission describes behaviour support assessment, including functional behaviour assessment, as the foundation for determining the strategies in a behaviour support plan (). In other words, the assessment comes first; the plan's strategies flow from what it finds. A plan written without this understanding is, at best, a guess.
Why does behaviour have a function?
Positive behaviour support rests on a simple, evidence-based premise: behaviour is communication. A behaviour that looks challenging from the outside is usually an effective way — sometimes the only reliable way available to the person — of meeting a real need. When we understand that need, we can teach and support a safer, more effective way to meet it.
Behaviour analysts generally group the functions of behaviour into a small number of categories:
A single behaviour can serve more than one function, and the same function can be met by very different behaviours. This is why assessment matters: two people who hit out may be doing so for entirely different reasons, and the support each needs is therefore different.
What happens during an FBA?
A functional behaviour assessment draws on several sources of evidence so the practitioner is not relying on any single viewpoint:
- Interviews with the person, their family and the people who support them.
- Direct observation across the settings where the behaviour does and does not occur.
- Record review — incident data, health information, previous reports and plans.
- Analysis of antecedents and consequences — what tends to happen before a behaviour (triggers and setting events) and what follows it (what the behaviour achieves).
From this, the practitioner develops a formulation: a working explanation of the behaviour, the needs behind it, and the conditions that make it more or less likely. Health, communication, sensory and environmental factors are all considered, because a behaviour of concern can be the visible tip of an unmet clinical need — pain, a communication barrier, or an overwhelming environment.
How does the FBA connect to the behaviour support plan?
The NDIS recognises two types of behaviour support plan. An interim behaviour support plan is a short document produced quickly to keep the person and others safe and to lower immediate risk. A comprehensive behaviour support plan follows the functional behaviour assessment and includes a detailed formulation, proactive strategies, plans to teach new skills, and steps to reduce and eventually remove any restrictive practices ().
The comprehensive plan is where the assessment does its work. Because the practitioner understands the function of the behaviour, the plan can:
- Change the environment so triggers and setting events are less likely (proactive strategies).
- Teach replacement skills — often communication skills — that meet the same need more safely and effectively.
- Improve quality of life — the central goal of positive behaviour support — so the person has more of what they need and value.
- Reduce and eliminate restrictive practices over time, with clear steps rather than open-ended use.
Who can carry out an FBA?
Functional behaviour assessment is a regulated activity. Only a behaviour support practitioner the NDIS Commission considers suitable may conduct an FBA or write a behaviour support plan — a practitioner cannot do this work, even under supervision, until they have been deemed suitable (). The Commission's Positive Behaviour Support Capability Framework sets out the competencies practitioners are assessed against ().
Evidence at a glance
Read these sources directly; this article is general information, not individual clinical advice.
Frequently asked questions
What is the difference between a behaviour and its function?
The behaviour is what a person does; the function is why they do it — the need it meets. Two people can show the same behaviour for different functions, and one function can be met by very different behaviours. A functional behaviour assessment identifies the function so support targets the underlying need.
What are the main functions of behaviour?
Behaviours of concern generally serve one or more functions: escaping or avoiding something aversive, gaining attention or social interaction, accessing a preferred item or activity, or meeting an internal sensory need. A behaviour can serve more than one function at once.
Is an FBA the same as a behaviour support plan?
No. The functional behaviour assessment is the assessment that explains why a behaviour happens. The behaviour support plan is the document that sets out strategies. A comprehensive behaviour support plan is built on the findings of the FBA.
Who is allowed to do a functional behaviour assessment under the NDIS?
Only a behaviour support practitioner considered suitable by the NDIS Quality and Safeguards Commission can conduct an FBA or write a behaviour support plan. Practitioners cannot do this work until the Commission has deemed them suitable.
How does an FBA help reduce restrictive practices?
By identifying the need a behaviour meets, an FBA lets the plan teach safer ways to meet that need and change the environment that triggers it. Meeting the underlying need reduces the situations where restrictive practices might otherwise be used, supporting their reduction and elimination over time.
Working with Align Network
Align Network's conduct functional behaviour assessments and develop interim and comprehensive behaviour support plans, working alongside our and teams where communication and sensory needs sit behind a behaviour of concern. To discuss an assessment, .
Contact Align Network today
Contact Align Network for specialist behaviour support, plan management, or allied health coordination.