Acceptance and commitment therapy (usually pronounced as the word “act” rather than the initials “A-C-T”) is a form of clinical behavioural analysis developed in 1986 by psychologists Steven Hayes, Kelly Wilson, and Kirk Strosahl. Originally called comprehensive distancing, it gets its current name from one of its core messages: the injunction to accept what is out of one’s personal control and commit to action that improves and enriches one’s life. Thus, ACT:

  1. Is an empirically-based set of psychological interventions that
  2. Uses mindfulness skills to develop psychological flexibility and
  3. Helps clarify and direct values-guided behaviour (Carrasco, 2013; Wikipedia, 2013; Harris, 2013).

What are ACT’s goals?

ACT aims to maximise human potential in order to create a rich and meaningful life, while accepting the pain that inevitably goes with it. It teaches those practicing it – let’s say that’s us – to accept things that are out of our control (this does not mean that we approve them) without evaluation or attempts to change them (unlike in Cognitive Behavioural Therapy), while committing to taking action that enriches our life. ACT therapy achieves this by:

  1. Helping us to clarify what is genuinely important and meaningful (that is, our values) and to use that knowledge to inspire and guide us to set life-enriching goals;
  2. Teaching psychological skills, known as mindfulness skills, for handling painful thoughts, feelings, urges, images, and memories (called private experiences) in such a way that they have much less impact on us. Developing a new mindful relationship with such experiences frees us to take action consistent with our values (Harris, 2006; Carrasco, 2013; Harris, 2009).

What is the underlying philosophy of ACT?

ACT is based on the pragmatic philosophy of Relational Frame Theory (RFT), a comprehensive theory of language and cognition that is derived from behaviour analysis. While traditional models of language and cognition go for an information transmission system, RFT uses a functional, contextualistic approach to understand complex human behaviour such as language and thought (Wikipedia, 2013; Fox, 2013).

Translated into simpler language, the above paragraph means that RFT refers to the way that the stimulus functions of a thing or event tend to get transferred to the word used to describe it. For instance, let’s say that you are afraid of snakes. Every time you see one, you experience a knot of fear in your stomach, you break out into an anxious sweat, and you have an overwhelming desire to run away. RFT understands that if someone merely utters the word “snakes” in your presence (the stimulus), you are likely to experience the same fear, anxiety, and desire to run as if you were confronted by a live snake.

Because all of us as human beings contain a huge storehouse of anxiety hidden in our personal histories, we also have a wealth of potential anxiety that could be experienced in our personal futures. In the present, thoughts can occur that remind us of anxiety we experienced in the past, and we may anticipate anxiety that could occur in the future. Thus, according to the principles of RFT, words become causes of pain. We hear someone talking about their grief from losing their father, and we re-experience our own similar grief. All that we have been exposed to is the other person’s words; we haven’t just experienced another bereavement, but the words of grief we are hearing evoke automatic thoughts and feelings as though the death were occurring right here and now.

We tend to take these words, these thoughts, literally, rather than observing them as thoughts. Thus language and thought ends up being able to hurt us, because through it, pain can be brought to our minds at any time. It cannot be avoided. The more we try to avoid the painful experience (through distraction, repression, substance abuse, and many more short-term strategies), the more it lingers, causing us anxiety, fear, sadness, pain, shame, and other difficult emotions. If we didn’t have language, we could not call up a negative past, nor anticipate a negative future. But the way our minds tend to deal with this pain makes things worse. We tend, as human beings, to set up an unwritten rule that suffering is bad, that the absence of suffering is good, and that if something is bad, we should try to get rid of it by acting on it directly (NWLCB Training, n.d.).

Enter Acceptance and Commitment Therapy. Working with the RFT model of language and cognition above, ACT helps people to relieve their suffering by dealing with painful experiences and thoughts – which RFT and ACT both acknowledge cannot be controlled long-term – by accepting them, and committing to actions which create a rich and purpose-filled life. Thus, the underlying philosophy of ACT (that is: RFT) is pragmatic, and precise, relying on just a few basic concepts to account for language and thought, with directly observable principles. It has direct applied and clinical applications, and is based on empirical research. Proponents say that it is taking behavioural science into exciting new directions with profound implications for almost every topic relating to complex human behavior (Wikipedia, 2013; Fox, 2013).

Where does ACT “sit” within schools of therapy?

Russ Harris, a general practitioner-turned-psychotherapist who has actively promoted the concepts of ACT through his writings, web presence, and training workshops, has commented that ACT is hard to describe, but can best be thought of as an “existential humanistic cognitive behaviour therapy” (Harris, 2009, p. 21). ACT is one of the “third wave” behavioural therapies, along with Dialectical Behaviour Therapy (DBT), Mindfulness-Based Cognitive Therapy (MBCT), and Mindfulness-Based Stress Reduction (MBSR) (you can read a bit about these in the MHA Mindfulness course). All four focus on the development of mindfulness skills.

Waves of behaviour therapies

So if ACT is the third wave, what were the first and second waves, you ask? Good question. The “first wave” of behavioural therapies, while started in the 1920s, became well-known in the fifties and sixties. These therapies looked at observable behavioural change and were characterised by their techniques of operant and classical conditioning: what is traditionally known as behaviourism. The “second wave” began in the seventies when practitioners allowed cognitive interventions to be included, and therapies such as Rational-Emotive Behaviour Therapy (REBT) and Cognitive Behaviour Therapy (CBT) grew in popularity, the latter eventually coming to dominate the “wave” (Harris, 2006).

Differences between ACT and other behaviour therapies

Clearly, there has been a growing trend to allow increasingly broader aspects of the client to come under study. Classical behaviourism, the first wave, looked only at behaviour. Therapies such as REBT and CBT in the second wave included both behaviour and cognition (thought and belief) as valid aspects to study in order to understand a human being. Third wave therapies, in their focus on mindfulness, additionally allow the aspect of awareness (that is, an aspect larger than the Western conception of “mind”) as a valid focus.

Within the current wave, ACT differs from the other therapies in several ways. First, MBSR and MBCT (the mindfulness approaches to stress reduction and cognitive therapy) are chiefly manualised protocols, designed to help groups of people in the treatment of stress or depression. DBT is often a combination of group skills training and individual therapy, created particularly to help those with Borderline Personality Disorder (Baer, 2003). Conversely, ACT can be used with a variety of clinical populations – as individuals, couples, or groups – in therapy sessions which can be brief, medium-term, or long-term.

ACT encourages therapists to create or individualise their own mindfulness techniques (even co-creating them with clients) rather than relying on manualised procedures. And ACT views formal mindfulness meditation as only one way within a wide range of methods to teach mindfulness skills (Harris, 2006).


  • Baer, R. (2003). Mindfulness training as a clinical intervention: A conceptual and empirical review. Clinical Psychology: Science and Practice, 10 (2), 125 – 143).
  • Carrasco, J. (2013). Acceptance and commitment therapy. Retrieved on 15 July, 2013, from: hyperlink.
  • Fox, E. (2013). Advantages of RFT. Association for Contextual Behavioral Science. Retrieved on 16 July, 2013, from: hyperlink.
  • Harris, R. (2013). Acceptance and commitment therapy. ACT Mindfully. Retrieved on 15 July, 2013, from: hyperlink.
  • Harris, R. (2009). Mindfulness without meditation. HCPJ (Healthcare Counselling and Psychology Journal). October, 2009, pp 21-24. Retrieved on 15 July, 2013, from: hyperlink.
  • Wikipedia. (2013). Acceptance and commitment therapy. Wikipedia: Wikimedia Foundation, Inc. Retrieved on 15 July, 2013, from: hyperlink.

This article was adapted from the Mental Health Academy course “Acceptance and Commitment Therapy”. This course covers the basic concepts and techniques of ACT, and examines how and why it may be effective with clients. Click here for more information.