The COM-B Model: A Practical Guide to Changing Behaviour

When it comes to changing behaviour—whether in public health, workplace dynamics, or personal habits—we often jump straight to goals. Eat healthier. Walk more. Drive less. But if we want real, lasting change, we need to get specific about the behaviour and understand what truly drives it.

That’s where the COM-B model comes in.

Developed by researchers at University College London (UCL), the COM-B model provides a clear, evidence-based framework for behaviour change. At its core, the model tells us that behaviour (B) occurs when three conditions are met: Capability (C), Opportunity (O), and Motivation (M).

Let’s break this down.

Step 1: Define the Behaviour

Behaviour is any action a person takes in response to internal or external stimuli. It’s essential to differentiate between behaviours, the factors that influence them, and the outcomes we want to achieve.

Start by asking: What is the specific behaviour we want to change?

Avoid being too broad. Instead of "increase physical activity," try "walk 10,000 steps a day."

Then, specify:

• Who performs the behaviour?
• What exactly do they do?
• When, where, how often, and with whom?

This detailed description sets the stage for a targeted intervention.

Step 2: Understand the Behaviour Using COM-B

Behaviour doesn’t happen in isolation. COM-B helps us understand the underlying conditions that must be in place.

Capability: Do they have the physical and psychological ability?

• Physical: Strength, skills, stamina
• Psychological: Knowledge, cognitive skills, decision-making ability

Opportunity: Does their environment support the behaviour?

• Physical: Time, resources, access
• Social: Norms, peer influence, cultural context

Motivation: Are they driven to do it?

• Reflective: Planning, decision-making, beliefs
• Automatic: Habits, emotions, instincts

A COM-B diagnosis identifies which component(s) need to change. If someone doesn’t walk daily, is it because they lack motivation, don’t know how far 10,000 steps is, or don’t have time or safe spaces to walk?

Step 3: Identify Intervention Types

Once we know what needs to change, we match it with effective strategies. The Behaviour Change Wheel outlines nine intervention types:

• Education: Increase knowledge (e.g., benefits of walking)
• Persuasion: Use emotion or imagery (e.g., social media stories of success)
• Incentivisation: Offer rewards (e.g., fitness challenges)
• Coercion: Introduce penalties (e.g., higher insurance for inactivity)
• Training: Build skills (e.g., using a step tracker)
• Restriction: Set rules (e.g., car-free zones)
• Environmental restructuring: Change the physical or social context (e.g., create walking paths)
• Modelling: Show role models (e.g., leaders walking to work)
• Enablement: Provide support/resources (e.g., free pedometers)

Each intervention type links to specific COM-B components. For instance, to address low psychological capability, you might combine education, training, and enablement.

Step 4: Choose Policy Options

Interventions need to be implemented effectively. The Behaviour Change Wheel offers seven policy options:

• Guidelines
• Environmental/social planning
• Communication/marketing
• Legislation
• Regulation
• Fiscal measures
• Service provision

For example, encouraging mask-wearing could involve education (signs explaining usage), persuasion (emphasising community protection), environmental restructuring (providing masks at entrances), and legislation (mandating mask use).

Step 5: Evaluate with APEASE

Not every intervention is feasible. Use the APEASE criteria to assess:

• Acceptability
• Practicability
• Effectiveness
• Affordability
• Spillover effects
• Equity

This ensures that the interventions chosen are realistic, cost-effective, and inclusive.

Step 6: Select Behaviour Change Techniques (BCTs)

BCTs are the active ingredients of an intervention. They are specific, observable, and replicable actions like:

• Instruction on how to perform a behaviour
• Demonstration
• Adding objects to the environment

Using tools like the BCTTv1 taxonomy, you can map BCTs to intervention types, ensuring your approach is grounded in evidence.

Real-Life Examples: From Theory to Practice

Let’s say you want to increase active travel in your city. You narrow it down to one specific behaviour: "Walk 10,000 steps every day."

COM-B Diagnosis:

• Capability: Most people can walk but may not know what 10,000 steps means.
• Opportunity: Safe paths may be lacking; work schedules may limit time.
• Motivation: Competing priorities or lack of enjoyment.

Intervention Types:

• Education (explain benefits)
• Environmental restructuring (build paths)
• Persuasion (social media stories)
• Enablement (provide apps or trackers)

Policy Options:

• Communication campaigns
• Infrastructure planning
• Service provision (apps, events)

BCTs:

• Track steps with an app
• Set daily reminders
• Offer feedback and encouragement

At Diversido, we've applied this framework in real-world projects. For example, in the development of a habit tracking app, we used COM-B to ensure users had the capability (knowledge and tools), opportunity (reminders, accessible UX), and motivation (progress tracking, positive reinforcement) to build healthy routines.

In our work with SST, aimed at improving learning outcomes, we utilised the COM-B framework to design features that enhance student engagement and persistence. We identified gaps in psychological capability (study skills), physical opportunity (access to resources), and both reflective and automatic motivation, and targeted these gaps with interventions such as gamified milestones, peer comparison, and structured learning paths.

In business settings, COM-B is equally relevant. Want employees to follow new cybersecurity protocols? Make sure they understand the risks (education), have easy-to-follow processes (environmental restructuring), and see peers valuing it (modelling and social opportunity). Trying to reduce meeting overload? Introduce clear guidelines (restriction), model better behaviour from leadership, and restructure calendars to support focus time.

Final Thoughts

The COM-B model and the Behaviour Change Wheel offer a structured, practical approach to designing interventions that work. Whether you're in public health, education, tech, or HR, understanding the why behind behaviour is the first step to changing it.

Start small. Get specific. And use evidence, not assumptions, to guide your next behaviour change project.

For more on COM-B and behavioural science, explore the Behaviour Change Wheel book or UCL Behaviour Change courses.