Hackett Continuum: Understanding Harmful Sexual Behaviour

The Hackett continuum is a model from Professor Simon Hackett (2010) that places children's sexual behaviour on a range from normal, through inappropriate, problematic and abusive, to violent. Professionals use it to describe a specific behaviour in context, looking at age, development, consent, power and persistence, so they can respond in proportion without labelling the child.

What harmful sexual behaviour means

The definition most UK safeguarding procedures use comes from Hackett (2014): sexual behaviours expressed by children and young people under the age of 18 that are developmentally inappropriate, may be harmful towards self or others, or be abusive towards another child, young person or adult. The NSPCC puts it more briefly: developmentally inappropriate sexual behaviour displayed by children and young people which is harmful or abusive.

Two points matter for your team. First, sexual development is normal: plenty of behaviour that makes adults uncomfortable is expected for a child's age. Second, the NSPCC is clear that HSB is harmful to the child who displays it as well as the people it is directed towards. Both are children, and both need a safeguarding response.

Hackett's continuum: the five points

Hackett set out the continuum in a 2010 chapter, "Children, young people and sexual violence", in Children Behaving Badly? (edited by Barter and Berridge). It also underpins the NSPCC's Harmful Sexual Behaviour Framework.

1. Normal: developmentally expected and socially acceptable. Consensual, mutual and reciprocal.
2. Inappropriate: a single instance, or behaviour acceptable within a peer group but in the wrong context. Generally consensual and reciprocal.
3. Problematic: developmentally unusual and socially unexpected. No overt victimisation, but consent may be unclear, power may be unequal and there may be compulsivity.
4. Abusive: victimising intent or outcome, misuse of power, coercion or force. Informed consent is lacking or cannot be freely given.
5. Violent: physically violent sexual abuse that is highly intrusive.

The value of the continuum is that it stops behaviour being sorted into "fine" or "abuse". Most of what staff see sits somewhere in between, and the right response depends on where.

Describe the behaviour, not the child

A child whose behaviour sits at the problematic point today is still a child, often with unmet needs of their own. NICE guideline NG55 asks professionals to focus on the child or young person as an individual and not on the presenting behaviour, and notes that inappropriate sexualised behaviour is often an expression of other problems or vulnerabilities.

To place a behaviour on the continuum, staff look at the context:

• Age and development: developmental ability as well as chronological age. A learning disability changes what is expected.
• Consent: did everyone involved freely give it, and were they able to?
• Power: is there a difference in age, size, ability or status?
• Persistence: is it a one-off, or does it continue after redirection?
• Secrecy and pressure: were there threats, bribes or a request to keep it secret?

It shows in the language your team uses. "Jordan kept making sexual comments to a younger resident after being asked to stop" is something a manager can act on. "Jordan is a predator" is a label that follows a child through every file they ever have.

Tools used alongside the continuum

Brook Sexual Behaviours Traffic Lights. Brook's tool sorts sexual behaviours in children and young people up to 18 by age group into green (typical and developmentally appropriate), orange (cause concern, for example through persistence or an inequality in age, power or ability) and red (indicate or cause harm). You may see the middle band called amber elsewhere. Brook adapted it for UK use, updated it in April 2026 with more guidance on responding and on digital behaviours, and requires professionals to complete its training before using it. It supports professional judgement rather than replacing it.

AIM assessment models. The AIM (Assessment Intervention Moving on) Project began in Manchester in 2000. Its AIM3 model assesses young people aged 12 to 18 who have displayed HSB, with a separate model for under-12s. These are specialist assessments by trained practitioners within a multi-agency response, not tools for staff on shift.

Responding when something happens

Your own safeguarding policy comes first. The NSPCC's guidance on managing incidents gives a sensible order:

1. Stay calm and stop the behaviour safely. If anyone is in immediate danger, call 999.
2. Make everyone safe: the child who has been harmed and the child displaying the behaviour.
3. Listen without judging. Talk calmly and avoid language that makes a child feel judged or criminalised. Don't question them in detail; that is for the professionals who may need to investigate.
4. Record factually and promptly: what you saw and heard, the words used, date, time, place, who was present, any imbalance of power and whether it appeared consensual. Labels don't belong in the record. Our defensible documentation training covers this in depth.
5. Pass it to your safeguarding lead the same day. They decide, with children's social care, whether a referral is needed, and involve the police where a crime such as sexual assault is alleged, in line with your local multi-agency arrangements.
6. Plan for safety. A proportionate safety plan covers risks to and from the child, involves the child and their network, and is reviewed regularly.

Parents and carers should be told their child has been affected, as long as this doesn't put the child at further risk.

Technology-assisted HSB

Technology-assisted HSB (TA-HSB) is when children and young people use the internet or other technology to engage in sexual activity that may be harmful to themselves and others, such as making or sharing nude images, online sexual harassment or age-inappropriate use of pornography. NSPCC research (Hollis and Belton, 2017) found that 46% of 275 children and young people assessed by one specialist service showed some TA-HSB. The same continuum applies online: age, consent, power and persistence still decide where a behaviour sits.

Why staff training matters

HSB goes wrong in two directions. Under-react, and a child keeps being harmed. Over-react, and a child with typical behaviour is treated as an abuser, which NICE warns can lead to unnecessary and stigmatising referrals. A shared language helps your team judge behaviour consistently across shifts.

In England, Ofsted inspects children's homes, fostering services and schools on how well they keep children safe, including from harm caused by other children. Keeping Children Safe in Education 2026, in force for schools and colleges in England since 1 September 2026, covers child-on-child abuse, including sexual violence, sexual harassment and harmful sexual behaviour. Wales, Scotland and Northern Ireland have their own guidance and inspectorates (CIW, the Care Inspectorate and RQIA).

For further reading, see the NSPCC's guide to understanding harmful sexual behaviour, NICE guideline NG55 and Keeping Children Safe in Education on gov.uk.

How Kasorb can help

Our harmful sexual behaviour training is a one-day course for staff working with children and young people, including children's home teams, foster carers, school staff and youth workers. It runs live online, or on-site on request, at one flat rate for the group. It covers typical, problematic and harmful sexual behaviour, Hackett's continuum, technology-assisted HSB, early intervention, safeguarding the young person and others, and developing interventions and care plans. Learning is checked through discussion and scenarios, and certificates of completion, valid for two years, are emailed the next day. If you are deciding who leads on this in your service, see our guide to the designated safeguarding lead role.

This guide summarises the law and guidance; it isn't legal advice.

FAQs

What is the Hackett continuum?

It is a model developed by Professor Simon Hackett in 2010 that places children's sexual behaviour on a range from normal to violent. Professionals use it to describe a behaviour in context, including age, development, consent and power, so they respond in proportion.

What are the five stages of Hackett's continuum?

Normal, inappropriate, problematic, abusive and violent. Normal behaviour is developmentally expected and mutual. Inappropriate behaviour is usually a one-off or out of context. Problematic behaviour is developmentally unusual, with unclear consent or unequal power. Abusive behaviour involves coercion or misuse of power, and violent behaviour involves physical violence.

Is the Brook Traffic Light Tool the same as Hackett's continuum?

No. Brook's Sexual Behaviours Traffic Lights sorts behaviours by age group into green, orange and red, and needs Brook training before use. Hackett's continuum has five points from normal to violent. Many services use them together, alongside professional judgement and their local safeguarding procedures.

What should staff do if a child displays harmful sexual behaviour?

Stay calm, stop the behaviour safely and make every child involved safe, including the child who displayed it. Call 999 if anyone is in immediate danger. Record exactly what you saw and heard, without labels, and pass it to your safeguarding lead the same day so they can follow your local multi-agency procedures.