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The COM-B model of behaviour is a well-know framework used to identify what needs to change in order for a behaviour change intervention to work.

The model focuses on three components deemed critical for producing and changing behavior: Capability, Opportunity, and Motivation. Each component is broken down into two parts.


The knowledge, skills, and abilities to engage in the behavior.

  1. Psychological Capability: our mental strength, skills, or stamina

  2. Physical Capability: our physical strength, skills, or stamina


The external factors which make doing a particular behaviour possible.

  1. Physical Opportunity: such as time, location, and resources

  2. Social Opportunity: such as cultural norms and social cues


The internal processes which influence our decision making and behaviours.

  1. Reflective Motivation: reflective processes, such as making plans and evaluating things that occurred in the past

  2. Automatic Motivation: automatic processes, like desires, impulses and inhibitions

According to the COM-B model, all these three conditions are needed for a behavior to occur.

This model is useful for understanding what needs to be modified in order to facilitate behaviour change. Once it is clear what aspect needs to be changed, the Behaviour Change Wheel can help understand how to make these changes.

The Behaviour Change Wheel (BCW)

The BCW uses the COM-B components of Capability, Opportunity and Motivation to provide seven "policy categories" and nine "intervention functions", which can be used to develop effective behaviour change interventions.

The Theoretical Domains Framework (TDF) builds on the COM-B with the purpose of further uncovering the barriers and facilitators of behavior change. You can find more information in this post!


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