The Association for Contextual Behavioral Science (ACBS) is a worldwide nonprofit professional membership organization associated with acceptance and commitment therapy (ACT), and relational frame theory (RFT) among other topics. The term "contextual behavioral science" refers to the application of functional contextualism to human behavior, including contextual forms of applied behavior analysis, cognitive behavioral therapy, and evolution science. In the applied area Acceptance and Commitment Therapy is perhaps the best known wing of contextual behavioral science, and is an emphasis of ACBS, along with other types of contextual CBT, and efforts in education, organizational behavior, and other areas. ACT is considered an empirically validated treatment by the American Psychological Association, with the status of "Modest Research Support" in depression and "Strong Research Support" in chronic pain, with several others specific areas such as psychosis and work site stress currently under review. ACT is also listed as evidence-based by the Substance Abuse and Mental Health Services Administration of the United States federal government which has examined randomized trials for ACT in the areas of psychosis, work site stress, and obsessive compulsive disorder, including depression outcomes. In the basic area, Relational Frame Theory is a research program in language and cognition that is considered part of contextual behavioral science, and is a focus of ACBS. Unlike the better known behavioral approach proposed by B.F. Skinner in his book Verbal Behavior, experimental RFT research has emerged in a number of areas traditionally thought to be beyond behavioral perspectives, such as grammar, metaphor, perspective taking, implicit cognition and reasoning.