Knowledge base Updated 2 November 2026 2 views

Acceptance and Commitment Therapy

A behavioural therapy that works on the relationship a person has with their thoughts and feelings rather than on the content of those thoughts, aiming at psychological flexibility and action guided by personal values.

Definition

Acceptance and Commitment Therapy (ACT) targets psychological flexibility: the ability to stay in contact with the present moment and to change or persist in behaviour according to what one values.

It differs from CBT in a specific way. Where CBT often asks whether a thought is accurate, ACT asks whether responding to it as though it were literally true is workable. The content of the thought is left alone.

History

Developed by Steven Hayes and colleagues from the 1980s, growing out of Relational Frame Theory, a behaviour-analytic account of language and cognition.

It is usually grouped with DBT and mindfulness-based approaches as a third wave of behaviour therapy, though the label obscures how different those treatments are from each other.

Theory

Six interlocking processes, usually drawn as a hexagon:

Acceptance: allowing unwanted internal experience rather than struggling with it.
Cognitive defusion: noticing a thought as a thought.
Contact with the present moment.
Self-as-context: the perspective from which experience is observed.
Values: chosen directions, not goals to be achieved.
Committed action.

The theoretical claim underneath is that experiential avoidance — trying not to have unwanted thoughts and feelings — is a major driver of psychopathology and often makes the problem worse.

Research

The evidence base is substantial and growing, with support across chronic pain, anxiety, depression, psychosis and workplace stress.

Head-to-head against CBT, results are broadly comparable rather than superior. Meta-analyses that restrict to high-quality trials find smaller effects than the wider literature suggests.

Mediation studies generally support psychological flexibility as a mechanism, though these are correlational and the measurement of flexibility is contested.

Applications

Widely used in chronic pain, where changing the pain is often not available and changing the relationship to it is. Also common in workplace interventions, in psychosis, and in brief formats.

A practical advantage is that it does not require the client to accept a disease model of their difficulty, which suits people who reject one.

Criticism

Relational Frame Theory is not widely accepted outside the behaviour-analytic community, and most clinicians using ACT do not use RFT.
The distinctiveness claim is weaker than advertised. Acceptance and defusion have close relatives in older therapies, and comparisons with CBT rarely show ACT ahead.
The flexibility measure has psychometric problems. The most-used questionnaire correlates so highly with distress measures that whether it captures a separate construct is unclear.
Values work can slide into vagueness in unskilled hands, producing sessions that feel meaningful and change nothing.

References

Hayes, S. C., Strosahl, K. D., & Wilson, K. G. (2011). Acceptance and Commitment Therapy (2nd ed.). Guilford Press.
A-Tjak, J. G. L., et al. (2015). A meta-analysis of the efficacy of ACT for clinically relevant mental and physical health problems. Psychotherapy and Psychosomatics, 84(1), 30-36.
Wolgast, M. (2014). What does the Acceptance and Action Questionnaire measure? Behavior Therapy, 45(6), 831-839.
Öst, L.-G. (2014). The efficacy of acceptance and commitment therapy. Behaviour Research and Therapy, 61, 105-121.

Written for PsychologyOrbit and reviewed before publishing. It is a summary for professionals and students, not clinical guidance, and it is not a substitute for the primary sources listed above.