Acceptance and commitment therapy (ACT, typically pronounced as the word "act") is a form of psychotherapy and a branch of clinical behavior analysis.[1] It is an empirically-based psychological intervention that uses acceptance and mindfulness strategies mixed in different ways[2] with commitment and behavior-change strategies, to increase psychological flexibility. The approach was originally called comprehensive distancing.[3] Steven C. Hayes developed acceptance and commitment therapy in 1982 in order to create a mixed approach which integrates both covert conditioning and behavior therapy.[4] There are a variety of protocols for ACT, depending on the target behavior or setting. For example, in behavioral health areas a brief version of ACT is called focused acceptance and commitment therapy (FACT).[5]