What Is the Transtheoretical Model?
The Transtheoretical Model (TTM) is a psychological model of behavior change proposing that people move through five sequential stages as they adopt a new behavior: Precontemplation, Contemplation, Preparation, Action, and Maintenance. Developed by James Prochaska and Carlo DiClemente at the University of Rhode Island, the model was first published in 1983 in Psychotherapy: Theory, Research, and Practice and expanded in their 1994 book Changing for Good.
The TTM is the most widely cited behavior change model in health promotion research. Painter, Borba, Hynes, Mays, and Glanz (2008, Health Education and Behavior) found that the TTM accounted for 33% of all theory-based health behavior research published between 2000 and 2005. No other model came close. The Theory of Planned Behavior was second at 13%.
The model’s descriptive claim (people vary in their readiness to change) is uncontroversial and widely accepted. The prescriptive claim (interventions should be matched to the person’s current stage) has failed repeatedly in controlled trials. This gap between the model’s popularity and its evidence base makes it one of the most debated frameworks in behavioral science.
The Five Stages
Stage 1: Precontemplation
The person has no intention to change within the next six months. They may not see the behavior as a problem, may feel powerless to change, or may have tried and failed before. Prochaska estimated that approximately 40% of at-risk populations are in precontemplation at any given time.
Stage 2: Contemplation
The person recognizes the problem and intends to change within the next six months, but has not committed to action. Contemplation is marked by ambivalence: the person weighs the pros and cons of changing. Prochaska described this as the stage where people “substitute thinking for action.” Some people remain in contemplation for years.
Stage 3: Preparation
The person intends to take action within the next 30 days and has taken some preliminary steps (buying running shoes, researching gym memberships, setting a quit date). This stage combines intention with early behavioral signals.
Stage 4: Action
The person has made observable behavioral changes within the past six months. This is the stage that most interventions target, and the stage that receives the most public attention. But Prochaska argued that action without adequate preparation leads to premature relapse.
Stage 5: Maintenance
The person has sustained the new behavior for more than six months and works to prevent relapse. Prochaska later proposed a sixth stage, Termination, where the person has zero temptation and complete self-efficacy, though this stage is rarely used in practice.
The Processes of Change
The TTM identifies ten cognitive and behavioral processes that facilitate movement between stages:
Experiential (cognitive) processes, most relevant in early stages:
- Consciousness raising. Increasing awareness about the causes and consequences of the behavior.
- Dramatic relief. Experiencing strong emotions related to the behavior (fear, hope, inspiration).
- Environmental reevaluation. Recognizing the impact of the behavior on others and the environment.
- Self-reevaluation. Reassessing self-image in relation to the behavior (“Is this who I want to be?”).
- Social liberation. Recognizing societal changes that support the new behavior (smoke-free zones, healthy food options).
Behavioral processes, most relevant in later stages:
- Self-liberation. Making a firm commitment to change (a public pledge, a signed contract).
- Counterconditioning. Substituting healthy behaviors for unhealthy ones (chewing gum instead of smoking).
- Stimulus control. Removing cues for the old behavior and adding cues for the new one.
- Reinforcement management. Using rewards for positive behavior change.
- Helping relationships. Seeking social support from friends, family, or professionals.
The TTM also incorporates two additional constructs: decisional balance (weighing the pros and cons of changing) and self-efficacy (confidence in ability to change across different situations). Prochaska proposed that pros of changing increase and cons decrease as people move through the stages. In a cross-sectional analysis of 12 problem behaviors, Prochaska and colleagues (1994) found that the pros of changing increased by approximately one standard deviation between precontemplation and action, while cons decreased by approximately half a standard deviation.
Where the TTM Has Been Applied
The TTM has been applied more broadly than any other behavior change model. Published applications span:
Smoking cessation. The TTM was originally developed from Prochaska and DiClemente’s research on how smokers quit. Their 1983 paper analyzed self-changers (people who quit without formal treatment) and found that they moved through identifiable stages using different processes at different points.
Physical activity. Marcus, Selby, Niaura, and Rossi (1992) adapted the stages of change model for exercise adoption. Their study of 1,093 worksite employees found that stage of change predicted physical activity levels and that different processes of change were associated with different stages, consistent with TTM predictions.
Diet and nutrition. Greene and colleagues (1999) developed a stages-of-change measure for dietary fat reduction and fruit and vegetable intake. The model has been incorporated into numerous dietary interventions.
Alcohol and substance use. The TTM has been widely used in addiction treatment settings, particularly in motivational interviewing (MI). William Miller and Stephen Rollnick’s MI approach, while not formally derived from the TTM, shares the assumption that readiness to change should guide intervention strategy.
Medical adherence. The TTM has been applied to medication compliance, diabetes self-management, cancer screening, and chronic disease management.
The Evidence Problem
Stage-Matching Does Not Work
The TTM’s central practical claim is that matching interventions to the person’s stage produces better outcomes than generic interventions. This claim has been tested extensively. The results are not favorable.
Cochrane Review (Cahill, Lancaster, & Green, 2010). This systematic review examined stage-based smoking cessation interventions. Across all included trials, the authors found no consistent evidence that stage-based interventions outperformed non-stage-based interventions. Some stage-based programs were effective, but no more effective than well-designed generic programs.
Riemsma and colleagues (2003). A systematic review in Health Technology Assessment concluded that evidence did not support the effectiveness of stage-based interventions for smoking cessation. The authors specifically noted that “there is limited evidence for the stage-based model in general.”
Bridle and colleagues (2005). A systematic review of stage-based interventions across multiple health behaviors found that the evidence “does not support the use of stage-based interventions” and that “the limitations of the evidence are profound.”
Robert West’s Critique
Robert West, a professor of health psychology at UCL and one of the architects of the COM-B model, published “Time for a change: Putting the Transtheoretical (Stages of Change) Model to rest” in 2005 in Addiction. West’s critique was systematic and pointed:
- The stage boundaries are arbitrary. Why six months for precontemplation? Why 30 days for preparation? The cutoffs have no theoretical or empirical justification.
- Stage transitions are not sequential. Many people skip stages entirely. Smokers frequently quit abruptly without moving through contemplation and preparation, a pattern West called “catastrophe theory” quitting.
- The model confuses description with prescription. Observing that people differ in readiness to change does not mean that tailoring interventions to stages improves outcomes.
- The processes of change lack specificity. Ten processes are too vague to guide specific intervention design compared to the 93 techniques in the BCT Taxonomy.
West estimated that at least half of successful smoking quits happen as unplanned attempts, contradicting the TTM’s sequential progression from contemplation through preparation to action.
Adams and White’s Physical Activity Critique
Adams and White (2005, Health Education Research) published “Why don’t stage-based activity promotion interventions work?” They identified several problems specific to physical activity: stage categorization was unreliable (people classified into different stages depending on the measure used), and the assumption that different processes drive different stages lacked empirical support in the exercise domain.
What the TTM Gets Right
Despite the evidence against stage-matching, the TTM contributed several ideas that remain useful:
Readiness matters. The descriptive observation that people differ in their readiness to change is empirically supported and practically important. A person who has never considered quitting smoking needs different engagement than someone who has already set a quit date. The TTM made this obvious point operationally precise.
Ambivalence is normal. The contemplation stage normalized the experience of wanting to change and simultaneously not wanting to change. Motivational interviewing built an entire clinical approach around navigating this ambivalence.
Relapse is part of the process. The TTM treated relapse not as failure but as a predictable part of behavior change. This shifted the clinical framing from blame to understanding.
Motivation is dynamic. The TTM emphasized that motivation changes over time and across contexts, challenging the static view of motivation that preceded it.
TTM vs. Other Models
| Feature | TTM | COM-B | Fogg (B=MAP) | Theory of Planned Behavior |
|---|---|---|---|---|
| Core idea | Stages of readiness | C + O + M = B | M + A + P = B | Attitudes + Norms + Control = Intention |
| Diagnostic power | Low (stages are descriptive) | High (six subcomponents) | Low (three factors) | Moderate (three predictors) |
| Intervention guidance | Weak (stage-matching fails) | Strong (BCW maps barriers to interventions) | Moderate (design heuristics) | Weak (identifies predictors, not solutions) |
| Evidence base | Descriptive: strong. Prescriptive: weak. | Strong (applied research) | Weak (limited formal testing) | Strong (prediction), weak (changing behavior) |
| Best use | Assessing readiness. Framing conversations. | Systematic intervention design | Product design, habit building | Predicting behavioral intentions |
Frequently Asked Questions
What is the Transtheoretical Model? The Transtheoretical Model (TTM) is a psychological model of behavior change developed by James Prochaska and Carlo DiClemente. It proposes that people move through five stages when changing behavior: Precontemplation (not considering change), Contemplation (considering change), Preparation (planning to change soon), Action (actively changing), and Maintenance (sustaining the change). The model also identifies ten processes of change that facilitate stage transitions.
What are the five stages of change? The five stages are: (1) Precontemplation, where the person has no intention to change within six months. (2) Contemplation, where they intend to change within six months but remain ambivalent. (3) Preparation, where they plan to act within 30 days and have taken initial steps. (4) Action, where they have made observable changes within the past six months. (5) Maintenance, where they have sustained the change for more than six months.
Does stage-matching work? The evidence does not support stage-matching. The Cochrane Review by Cahill, Lancaster, and Green (2010) found no consistent evidence that stage-based smoking cessation interventions outperformed generic interventions. Multiple systematic reviews (Riemsma et al., 2003; Bridle et al., 2005) reached the same conclusion across multiple health behaviors. Stage-matched interventions can be effective, but they do not appear to be more effective than well-designed non-stage-based programs.
What is the difference between the TTM and COM-B? The TTM describes stages of readiness and recommends matching interventions to stages. COM-B diagnoses specific barriers to behavior (Capability, Opportunity, and Motivation deficits) and maps those barriers to intervention strategies through the Behaviour Change Wheel. COM-B provides more actionable diagnostic information. The TTM tells you someone is in contemplation. COM-B tells you they lack physical opportunity or automatic motivation.
Is the Transtheoretical Model still used? The TTM remains the most cited behavior change model in health promotion research and is still taught widely in health psychology, nursing, and public health programs. It is used clinically in motivational interviewing contexts to assess readiness and frame conversations about change. Its influence has declined among researchers who have adopted COM-B and the Behaviour Change Wheel, but it persists in clinical training and health promotion practice.
Sources and Further Reading
- Prochaska, J. O., & DiClemente, C. C. (1983). Stages and processes of self-change of smoking. Psychotherapy: Theory, Research, and Practice, 20(3), 161-173.
- Prochaska, J. O., & Velicer, W. F. (1997). The transtheoretical model of health behavior change. American Journal of Health Promotion, 12(1), 38-48.
- West, R. (2005). Time for a change: Putting the Transtheoretical (Stages of Change) Model to rest. Addiction, 100(8), 1036-1039.
- Cahill, K., Lancaster, T., & Green, N. (2010). Stage-based interventions for smoking cessation. Cochrane Database of Systematic Reviews, (11), CD004492.
- Adams, J., & White, M. (2005). Why don’t stage-based activity promotion interventions work? Health Education Research, 20(2), 237-243.
