Glossary
The Behaviour Change Wheel: A Complete Guide to Designing Interventions
What Is the Behaviour Change Wheel?
The Behaviour Change Wheel (BCW) is a systematic framework for designing behavior change interventions. It consists of three concentric layers: a diagnostic core (the COM-B model), a middle ring of nine intervention functions, and an outer ring of seven policy categories. Susan Michie, Maartje van Stralen, and Robert West developed the BCW. They published it in 2011 in Implementation Science. The 2014 guide was written by Michie, Lou Atkins and West.
Michie and colleagues built the BCW to solve a specific problem. They systematically reviewed 19 existing behavior change frameworks and found that none met all three criteria of usefulness: comprehensive coverage of all intervention types, coherent categorization (not mixing different levels of analysis), and linkage to an overarching model of behavior. They designed the BCW to satisfy all three.
The wheel gives teams a structured way to consider intervention options.
The Three Layers
Layer 1: COM-B (The Diagnostic Core)
COM-B proposes an interacting system involving: Capability (C), Opportunity (O), and Motivation (M), which can influence Behavior (B). Each component has two subcomponents, creating six diagnostic categories:
- Physical Capability. The physical skills, strength, or stamina needed. A stair-climbing task may exceed a person's current mobility or stamina.
- Psychological Capability. The knowledge, cognitive skills, or mental capacity required. Healthcare workers who cannot remember the correct hand hygiene protocol have a psychological capability deficit.
- Physical Opportunity. What the external environment provides: time, resources, locations, access, cues. For a gym-based program, distance or transport may restrict access; other forms of exercise may still be possible.
- Social Opportunity. Cultural norms, social cues, and interpersonal influences. Whether colleagues smoke during breaks. Whether friends encourage or mock healthy eating attempts.
- Reflective Motivation. Conscious processes: planning, goal-setting, evaluating pros and cons, forming intentions, identity beliefs.
- Automatic Motivation. Processes that happen without deliberation: emotional reactions, desires, impulses, habits. The craving for a cigarette. The automatic habit of reaching for a phone.
COM-B allows reciprocal influences. Capability and opportunity can affect motivation, and performing a behavior can change all three. Learning a skill, for example, may change both what someone can do and how willing they are to try.
Layer 2: Nine Intervention Functions
A COM-B assessment can suggest candidate intervention functions. The functions below describe broad purposes; their use requires evidence and judgment, not an automatic one-to-one prescription:
| Intervention Function | What It Does |
|---|---|
| Education | Increases knowledge and understanding |
| Training | Imparts skills through practice |
| Enablement | Reduces barriers beyond education/training (e.g., medication, behavioral support) |
| Persuasion | Uses communication to stimulate action |
| Incentivisation | Creates expectation of reward |
| Coercion | Creates expectation of punishment |
| Environmental Restructuring | Changes the physical or social context |
| Modelling | Provides examples to aspire to or imitate |
| Restriction | Reduces opportunity for competing behaviors |
The authors drew precise distinctions between terms that overlap in everyday language. "Education" focuses on knowledge, not skills. "Training" focuses on skills, not knowledge. "Enablement" covers increasing means or reducing barriers beyond education, training or environmental restructuring (pharmacological support, behavioral counseling, prostheses).
Layer 3: Seven Policy Categories
Policies are actions by responsible authorities that enable or support interventions:
- Communication/marketing (mass media campaigns)
- Guidelines (treatment protocols, practice recommendations)
- Fiscal measures (taxes, subsidies)
- Regulation (voluntary agreements, industry standards)
- Legislation (laws, mandates)
- Environmental/social planning (town planning, infrastructure design)
- Service provision (establishing support services)
Policy categories can support several intervention functions. The original paper supplies mapping tables.
How to Use the BCW: The Eight-Step Process
Michie, Atkins, and West codified the process in their 2014 book. Three stages, eight steps.
Stage 1: Understand the Behavior
Step 1: Define the problem in behavioral terms. For example, replace a broad aim such as improving attendance with a specified behavior such as booking and attending an appointment.
Step 2: Select the target behavior. List all behaviors that could address the problem. Score them on likely impact, likelihood of change, spillover effects, and measurability. Choose and justify the target behavior or behaviors.
Step 3: Specify the behavior. Define who, what, when, where, how often, and with whom.
Step 4: Run the COM-B analysis. For each of the six subcomponents, assess whether it is a barrier. Use interviews, surveys, observation, or existing data. The Theoretical Domains Framework (TDF) can provide a more detailed vocabulary for barriers and facilitators.
Stage 2: Identify Intervention Options
Step 5: Identify intervention functions. Use the COM-B analysis to look up which intervention functions are relevant. For a physical opportunity barrier, consider whether environmental restructuring, restriction, or enablement addresses the actual obstacle.
Step 6: Identify policy categories. Determine which policies can support the chosen intervention functions.
At both steps, apply the APEASE criteria to shortlist options:
| Criterion | Question |
|---|---|
| Affordability | Can it be delivered at acceptable cost? |
| Practicability | Can it be delivered as designed in the real-world context? |
| Effectiveness | Does the evidence support it? Is it cost-effective? |
| Acceptability | Will the target population and stakeholders accept it? |
| Side-effects | What unintended consequences might occur? |
| Equity | Will it reduce or increase health inequalities? |
Stage 3: Select Content and Delivery
Step 7: Select behavior change techniques. Use the BCT Taxonomy v1 (93 techniques in 16 groupings, Michie et al., 2013, Annals of Behavioral Medicine) to specify the exact techniques that deliver each intervention function. Apply APEASE again.
Step 8: Select mode of delivery. Face-to-face versus distance. Individual versus group. Digital versus print. Apply APEASE again.
A Practical Example
Suppose people book a service but miss the appointment. Start by investigating what happens. Someone who cannot travel needs a different response from someone who cannot remember the date. A reminder may address one problem while leaving the other intact.
The wheel can help organize those options. Transport support or a different delivery format may address access; a reminder may address remembering. These are options to investigate and test, not conclusions that follow from the label alone. It may also be better to change the required behavior, such as replacing an unnecessary visit with another way to use the service.
A Published Application: StopApp
Fulton and colleagues used the Behaviour Change Wheel to develop StopApp, a web app intended to increase booking and attendance at NHS Stop Smoking Services. They investigated barriers and facilitators, used that analysis to select behavior change techniques, and assessed the app’s acceptability. Their 2016 development paper shows how the design process was used; it does not establish an improvement in attendance or quit rates.
Limitations and Criticisms
The original 2011 study evaluated classification reliability in tobacco control and obesity. Its authors explicitly called for research on whether the BCW improves the efficient design of effective interventions. Reliable classification is a different outcome from successful behavior change.
Applying the framework takes judgment. Available evidence may leave several plausible interventions, and the time required depends on the question and data already available. Interviews can help, but behavior, context and implementation should also be observed where feasible.
Evaluate benefits, costs, acceptability, unintended effects and equity in the intended population.
BCW vs. Other Frameworks
COM-B is the behavioral model at the wheel’s center. The full BCW adds intervention functions and policy categories. BCTTv1 supplies a separate vocabulary for specifying intervention content. These tools can be used together.
EAST and MINDSPACE offer shorter prompts for design discussions. The Fogg Behavior Model focuses on motivation, ability, and prompts. Their simplicity can help a team ask questions quickly, but ease of use does not establish effectiveness. Choose the amount of structure that helps answer the actual problem.
Frequently Asked Questions
What is the difference between COM-B and the Behaviour Change Wheel?
COM-B is the behavior model at the center. The full wheel adds nine intervention functions and seven policy categories to help consider responses.
How long does the BCW process take?
There is no fixed duration. A project with clear existing evidence requires different work from one that needs interviews, observation, or new testing. State which parts of the assessment are supported and which remain assumptions.
What are the APEASE criteria?
Affordability, Practicability, Effectiveness and cost-effectiveness, Acceptability, Side-effects and safety, and Equity. They help compare options, but judgment is still required.
Is the BCW only for health behavior?
The questions about capability, opportunity, and motivation can be asked in other settings. Evidence from a health application does not automatically establish results in a workplace, product, or environmental project.
Why it matters
The wheel can make intervention choices more explicit. Its value is in helping a team explain what it plans to change and why. The crucial work remains choosing a suitable behavior, understanding the people involved, and checking what happens.
Sources and further reading
- Susan Michie, Maartje M. van Stralen and Robert West (2011): The behaviour change wheel: A new method for characterising and designing behaviour change interventions
- Susan Michie, Lou Atkins and Robert West (2014): The Behaviour Change Wheel: A Guide to Designing Interventions
- Susan Michie, Michelle Richardson, Marie Johnston, Charles Abraham, Jill Francis, Wendy Hardeman, Martin P. Eccles, James Cane and Caroline E. Wood (2013): The Behavior Change Technique Taxonomy (v1) of 93 Hierarchically Clustered Techniques: Building an International Consensus for the Reporting of Behavior Change Interventions
Public Health England: Achieving behaviour change explains the APEASE criteria and their use in decisions.