Acceptance and Commitment Therapy (ACT) is a therapeutic process that looks to help a person identify what they truly value, accept that certain external factors may not be in their control, and also commit to engaging in behaviors that are based off of what they value– despite certain uncontrollable external factors . 
A core feature of ACT is the concept of functional contextualism.  This means that every behavior we engage in has a context, and some type of function that provides certain benefits.
For example: A person named Joe, who may be overwhelmed and stressed from work, may come home after a long day and drink a glass of wine. If Joe engages in this behavior occasionally, it probably wouldn’t impact domains of life– like career, relationships, leisure, or health–in the long run. The issue, however, could become that engaging in this behavior in excess may potentially impact their functioning.
In this example, if Joe drank multiple bottles daily to help relieve stress, the following consequences in his domains of life could happen:
- He may not function as well in his relationships,
- His health could deteriorate and lead to poor liver functioning
- He may lose the ability to participate in leisure activities
- If his motor and cognitive functioning is impaired, and they show up inebriated (or hungover) each day, it could impact their work by making it difficult for them to do their jobs adequately.
When counseling is approached through the lens of the ACT perspective, clients are able to explore the function and context of their behaviors, determine what they truly value in the different domains of life, and identify healthier ways to engage in order to be the best version of themselves.
The concept of functional contextualism that underlies ACT intervention is a Humanistic psychological theory. Humanistic psychology emphasizes:
- The importance of every human having free will
- That humans are innately good and looking towards a better life
- That humans are striving towards self-actualization
- That humans have their own subjective experiences 
By incorporating humanistic principles that look to provide a nonjudgmental space, that allows for the exploration of oneself, the person can identify the things that they subjectively value. This enables them to engage more effectively with others, and increase awareness around the function of their current behavioral patterns.
Functional contextualism, and how it ties in with Humanistic psychology, is important for a number of reasons, including the fact that everyone has their subjective experiences that inevitably cause differences in values based on those subjective experiences. Interventions based on ACT allows a person to work towards matching their ideal self to their actual current self.
Using the example from before, we can understand that Joe utilized alcohol as a way to cope with stress. If the exploration stage is conducted in a non-judgmental environment, the client and psychologist may be able to connect the reasoning for alcohol use to Joe’s desire for stress relief, and that it may be coming at the cost of damage to his health, his relationships becoming strained, and a decrease in ability to engage in leisure activities.
In therapy, Joe could identify that he doesn’t want to be a person that is negatively impacted by alcohol to the point of harming himself and impacting the domains of life mentioned earlier. Additionally, Joe may identify that one of the things that he values is his reliability as a person.
Through this process, Joe can begin to identify alternative strategies for stress relief , without the long-term ramifications as the previous behavior of excessive alcohol use. The end result of this scenario differs for each person–depending on their values and interests (i.e. one person in Colorado may relieve stress by way of hiking/walking in nature, while another person in Illinois may prefer to play indoor basketball for stress relief purposes.)
Acceptance and Commitment Therapy is a Humanistic counseling theory.. At the core, functional contextualism brings in the humanistic principle of subjective experience. That, along with the importance of understanding that each person has their own context, and that their behaviors had some function in that specific context.
By keeping functional contextualism in mind, it allows the therapy process to be more valuable by allowing a space for the client to be authentic, explore who they want to be within their own context, deepen awareness regarding their values, and identify the actions they want to take that are unique to their situation. ACT incorporates the concept that there is not one path to being a healthy human, and within the context of the counseling relationship, clients are able to discover how they uniquely desire to live life, truer to their values and closer to their authentic selves.
 Harris, R. (2009). ACT Made Simple: An Easy-To-Read Primer on Acceptance and Commitment Therapy. Oakland, CA: New Harbinger.
 McLeod, S. A. (2015, December 14). Humanism. Simply Psychology. https://www.simplypsychology.org/humanistic.html