A preview of COM-B 2.0

Robert West

Esther Flanagan

Susan Michie

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These slides are from a talk given at the Annual Conference of the Public Health Wales Behavioural Science Unit in November 2025

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COM-B 2.0 is due to be published early in 2026. This slide set provides a preview of some of its features.

• Explicitly capturing the distinction between individual-level and population-level COM-B
• Detailing specific sub-components of capability, opportunity and motivation
• More precise definitions of COM-B components

Aims of the presentation

https://com-b.org

1. Behaviour consists of all our physical actions, controlled by the brain.
2. At every moment, a person engages in a given behaviour when:
• they have the physical and psychological capability to do it
• they have the physical and social opportunity to do it, and
• they are more motivated to do it than any other behaviour they might have the capability and opportunity to do
3. Capability and opportunity both influence motivation
4. Motivation influences capability
5. Behaviour influences capability, opportunity and motivation

• When applying the COM-B model to a person at a given moment in time, capability and opportunity are like ‘logic gates’; if either is closed, the behaviour cannot occur.
• When predicting the occurrence or incidence of behaviour over a period of time or across more than one person, capability and opportunity are matters of degree that influence the behaviour

https://www.qeios.com/read/WW04E6.2

The COM-B model provides a basis for:

• explaining and predicting behaviour
• developing interventions to influence behaviour
• analysing interventions aimed at influencing behaviour
• examining how other, more specific, models and theories of behaviour relate to each other
• creating specific causal models of specific behaviours that include contexts

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1. ‘Individual-level’ COM-B is distinguished from ‘Population-level’ COM-B
2. COM-B components are more precisely defined and linked to the Behaviour Change Intervention Ontology (BCIO)
3. COM-B components are broken down into key influences that can form the basis for a detailed diagnosis of what needs to change to influence a given behaviour in a given population and context.

What’s new in COM-B 2.0?

1. Most applications of COM-B involve groups of people varying in size from families to whole populations.
2. Populations are best characterised as statistical distributions with means, medians etc, and measures of dispersion such as variance.
3. Therefore, population COM-B parameters are best represented as ‘variables’ with statistical properties, and causal relations between them as ‘functions’ linking these variables over specified time periods.

‘Individual’ versus ‘population’ COM-B

Example: Prevalence of attempts to stop smoking of adult tobacco smokers in England in e.g., November 2025

Level of understanding of smoking harms and benefits of quitting, and confidence in ability to quit

Level of desire and intention to stop smoking

Level of exposure to stop-smoking messaging and norms, and access to stop-smoking support

Prevalence of making a quit attempt

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Each variable can be operationalised and measures to yield a number to enter into the model. The functions can be obtained from regressions between the variables.

Capability variables

Opportunity variables

Motivation variables

1. Experience of using COM-B to develop interventions showed a need for a more specific set of COM-B variables to make a COM-B diagnosis and explicitly link these with the Behaviour Change Intervention Ontology and the Theoretical Domains Framework
2. Experience with using COM-B to create population-level models showed a need to frame COM-B components as measurable variables
3. Feedback from users of COM-B showed a need to clarify some of the COM-B components

1. Test the new COM-B variables and their links between the new COM-B variables and BCW intervention functions and Behaviour Change Techniques in workshops with researchers and practitioners
2. Use the new framework to develop and evaluate updated and improved tools for analysing behaviours and developing interventions

Upcoming resources

• Flanagan E, West R and Michie S ‘Making behaviour change interventions that work’ Silverback Publishing 2026*
• Michie S, West R and Flanagan E ‘The Behaviour Change Wheel 2^nd Edition’ Silverback Publishing 2026*
• Flanagan E, Michie S, Gould, A, West R ‘Using the CACTISS Tool to develop behaviour change interventions’ Qeios 2026*

*Titles and author lists to be confirmed

Thank you

https://whocc.pobl.tech/bsu/