Acceptance and Commitment Therapy, or ACT, is a contemporary form of cognitive behavioral therapy that employs mindfulness and acceptance strategies to increase psychological flexibility. Psychological flexibility is essentially the ability to be open, adaptable, and effective in the presence of difficult emotions or thoughts.

ACT is grounded in the belief that fighting or denying unpleasant emotions often exacerbates them. Instead of attempting to reduce or alter the frequency and form of these symptoms, ACT focuses on changing the relationship individuals have with their thoughts and feelings.