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Evidence rating
Cost rating
Review: January 2019

ASSIST (named for its trial: A Stop Smoking in Schools Trial), is a schools-based smoking prevention programme. It is a universal programme for children between the ages of 12 and 13. It is delivered in secondary schools, and aims to improve resilience and reduce the take-up of smoking.

The programme involves using a questionnaire to identify influential students within schools, and then recruiting them into the programme and delivering interactive skills and information training. These influential peer supporters then disseminate information positively and effectively to empower their friendship groups not to take up smoking. 

EIF Programme Assessment

Evidence rating

ASSIST has evidence of a short-term positive impact on child outcomes from at least one rigorous evaluation.

What does the evidence rating mean?

Level 3 indicates evidence of efficacy. This means the programme can be described as evidence-based: it has evidence from at least one rigorously conducted RCT or QED demonstrating a statistically significant positive impact on at least one child outcome.

This programme does not receive a rating of 4 as it has not yet replicated its results in another rigorously conducted study, where at least one study indicates long-term impacts, and at least one uses measures independent of study participants. 

Cost rating

A rating of 1 indicates that a programme has a low cost to set up and deliver, compared with other interventions reviewed by EIF. This is equivalent to an estimated unit cost of less than £100.

Child outcomes

According to the best available evidence for this programme's impact, it can achieve the following positive outcomes for children:

Preventing substance abuse

based on
2.64-percentage point reduction in proportion of participants smoking in the last week (self-report)
Improvement index: +6
This means we would expect the average participant in the comparison group who did not receive the intervention (ie, someone for whom 50% of their peers have better outcomes and 50% have worse outcomes), to improve to the point where they would have better outcomes than 56% and worse outcomes than 44% of their peers, if they had received the intervention.
Long-term A year later

Key programme characteristics

Who is it for?

The best available evidence for this programme relates to the following age-groups:

  • Preadolescents

How is it delivered?

The best available evidence for this programme relates to implementation through these delivery models:

  • Group

Where is it delivered?

The best available evidence for this programme relates to its implementation in these settings:

  • Secondary school

How is it targeted?

The best available evidence for this programme relates to its implementation as:

  • Universal

Where has it been implemented?

England, France, Scotland, Wales

UK provision

This programme has been implemented in the UK.

UK evaluation

This programme’s best evidence includes evaluation conducted in the UK.

Spotlight sets

EIF includes this programme in the following Spotlight sets:

  • School-based social & emotional learning

About the programme

What happens during delivery?

How is it delivered?
  • ASSIST is delivered in six sessions of varying length – one 20-minute session, three hour-long sessions, and two full-school-day sessions. These are delivered to groups of peer supporters by external trainers.
What happens during the intervention?
  • The programme involves four distinct phases:
    1. Students are nominated by their peers using a questionnaire completed by the whole year group.
    2. The most nominated 18%, balanced by gender, are then recruited to join the programme as peer supporters.
    3. These peer supporters will then participate in two days of training away from school where they will be given the skills and information that they need to perform their role. The training is very interactive and student-led. There is much emphasis on influence and persuasion – being empathetic, non-judgmental and understanding about the reasons why people smoke, as well as the benefits of making healthier choices. Students are encouraged to record their conversations in a diary which they bring to each of the follow-ups. These school-based sessions give students and trainers an opportunity to share progress and support each other while also refreshing skills and information.
    4. At the end of the programme the students are presented with a certificate, as is the school, which is left with a high-quality group of young health ambassadors.

What are the implementation requirements?

Who can deliver it?
  • This programme is delivered by a lead trainer with QCF-4/5 level qualifications, and two trainers also with QCF-4/5 level qualifications.
What are the training requirements?
  • Practitioners have 21 hours of programme training each. Booster training of practitioners is not required.
How are the practitioners supervised?

Practitioner supervision is provided through the following processes:

  • It is recommended that practitioners are supervised by one host agency supervisor (qualified to QCF-6 level).
  • It is recommended that practitioners are also supervised by one programme developer supervisor (qualified to QCF-6 level).
What are the systems for maintaining fidelity?

Programme fidelity is maintained through the following processes:

  • Training manual
  • Other printed material
  • Other online material
  • Face-to-face training
  • Fidelity monitoring.
Is there a licensing requirement?

Yes, there is a licence required to run this programme.

How does it work? (Theory of Change)

How does it work?
  • Smoking-related behavioural change in adolescents is propagated by trained peer supporters who promote the benefits of remaining smoke-free and the risks of smoking.
  • The programme teaches influential peer supporters’ ways of disseminating information positively and effectively, alongside conflict resolution methods, to empower their friendship groups not to take up smoking.
  • In the short term, peer supporters learn about the risks of smoking and the benefits of being smoke-free, and are trained to disseminate these messages in an ad-hoc way by looking for opportunities to include smoking facts in their everyday conversations with their friends.
  • In the long term, peer supporters develop leadership and communication skills and build personal resilience, and are more confident and less likely to take up smoking.
Intended outcomes

Preventing substance abuse


About the evidence

ASSIST’s most rigorous evidence comes from a cluster RCT which was conducted in the UK.

This study identified statistically significant positive impact on a number of child outcomes.

This programme is underpinned by one study with a level 3 rating, hence the programme receives a level 3 rating overall.

Study 1

Citation: Campbell et al., 2008
Design: Cluster RCT
Country: United Kingdom
Sample: 10,730 children recruited from 59 schools, with low number of smokers at baseline.
Timing: Post-test; 1-year follow-up; 2-year follow-up
Child outcomes: Reduced prevalence of smoking in the past week
Other outcomes: None measured
Study rating: 3

Campbell, R., Starkey, F., Holliday, J., Audrey, S., Bloor, M., Parry-Langdon, N., ... & Moore, L. (2008). An informal school-based peer-led intervention for smoking prevention in adolescence (ASSIST): a cluster randomised trial. The Lancet371(9624), 1595-1602.

Available at

Study design and sample

The first study is a rigorously conducted RCT. 

This study involved random stratified-blocked assignment (stratified by country; type of school; size of school; level of entitlement to free school meals) of schools to an ASSIST group or to a control group which continued their usual smoking education.  

This study was conducted in the UK, with a sample of 10,730 children recruited from 59 schools in the west of England and southeast of Wales. The sample was relatively diverse in terms of family affluence. Only a small proportion (6%) of children were smokers at baseline.


Smoking prevalence was measured using a questionnaire asking children to report on whether they had smoked in the past week (self-report).


This study identified statistically significant positive impact on a child outcome, which was reduced prevalence of smoking in the past week (at 1-year follow-up).

More Less about study 1

Other studies

The following studies were identified for this programme but did not count towards the programme's overall evidence rating. A programme receives the same rating as its most robust study or studies.

Audrey, S., Cordall, K., Moore, L., Cohen, D., & Campbell, R. (2004). The development and implementation of a peer-led intervention to prevent smoking among secondary school students using their established social networks. Health Education Journal, 63(3), 266-284.

Audrey, S., Holliday, J., & Campbell, R. (2008). Commitment and compatibility: teachers' perspectives on the implementation of an effective school-based, peer-led smoking intervention . Health Education Journal, 67(2), 74-90. Process evaluation

Audrey, S., Holliday, J., Parry-Langdon, N., & Campbell, R. (2006). Meeting the challenges of implementing process evaluation within randomized controlled trials: the example of ASSIST (A Stop Smoking in Schools Trial). Health education research, 21(3), 366-377.


Holliday, J. C., Rothwell, H. A., & Moore, L. A. (2010). The relative importance of different measures of peer smoking on adolescent smoking behavior: cross-sectional and longitudinal analyses of a large British cohort. Journal of Adolescent Health, 47(1), 58-66.

Holliday, J., Audrey, S., Moore, L., Parry-Langdon, N., & Campbell, R. (2009). High fidelity? How should we consider variations in the delivery of school-based health promotion interventions?. Health Education Journal, 68(1), 44-62. Process evaluation.

Hollingworth, W., Cohen, D., Hawkins, J., Hughes, R. A., Moore, L. A., Holliday, J. C., ... & Campbell, R. (2011). Reducing smoking in adolescents: cost-effectiveness results from the cluster randomized ASSIST (A Stop Smoking In Schools Trial). Nicotine & Tobacco Research, 14(2), 161-168.

Mercken, L., Moore, L., Crone, M. R., De Vries, H., De Bourdeaudhuij, I., Lien, N., ... & Van Lenthe, F. J. (2012). The effectiveness of school-based smoking prevention interventions among low-and high-SES European teenagers. Health education research, 27(3), 459-469.

Starkey, F., Audrey, S., Holliday, J., Moore, L., & Campbell, R. (2009). Identifying influential young people to undertake effective peer-led health promotion: The example of A Stop Smoking In Schools Trial (ASSIST). Health Education Research, 24 (6), 977-988.

Starkey, F., Moore, L., Campbell, R., Sidaway, M., & Bloor, M. (2005). Rationale, design and conduct of a comprehensive evaluation of a school-based peer-led anti-smoking intervention in the UK: the ASSIST cluster randomised trial [ISRCTN55572965]. BMC Public Health, 5(1), 43.

Starkey, F., Moore, L., Campbell, R., Sidaway, M., & Bloor, M. (2007). Erratum to: Rationale, design and conduct of a comprehensive evaluation of a school-based peer-led anti-smoking intervention in the UK: the ASSIST cluster randomised trial [ISRCTN55572965]. BMC Public Health, 7(1), 301.

Steglich, C., Sinclair, P., Holliday, J., & Moore, L. (2012). Actor-based analysis of peer influence in A Stop Smoking In Schools Trial (ASSIST). Social Networks, 34(3), 359-369.

Published February 2019   |   Last updated April 2021