A comprehensive treatise on how to understand complex language, and use language effectively as a behavior analyst. Language changes everything. From infancy through adulthood, language shapes how we live our lives and interact with other people, in increasingly complex ways. Language also shapes how we exist in the world as professionals—and how we operate as a profession. As behavior analysts working with others to effect change, words matter. A comprehensive understanding of complex language is therefore critical to practicing effectively as a behavior analyst. Understanding the functions of complex language, allows us to skillfully use language as an intervention tool. Relational frame theory (RFT) is a behavior analytic theory of human language. RFT suggests that the building block of human language and higher cognition is relating—in other words, the human ability to create links between one thing and another using words. Understanding and Applying Relational Frame Theory outlines the essential principles of RFT, and offers practical applications and tools to help clients live better lives and to establish the conditions necessary for all of us to thrive. With a central focus on establishing psychological flexibility, prosociality, and cooperative contexts for change, at all levels of analysis—from the self to overarching systems and cultures—in this book, you will: Learn the theoretical basis of RFT, including how relational operants are learned, from their roots in early social interactions to the complex relating of relations and relational networks seen in analogical and metaphorical reasoning. Explore how complex verbal repertoires affect individual behavior, introducing the development of the self and the influence of rule-governed behavior and private events. Examine relational framing in the context of groups—including the speaking and listening skills needed for supervision, mentorship, effective messaging, and prosociality within and between organizational systems. Discover the implications of applying a behavior analytic understanding of complex language to a variety of settings, including education, mental health, and business. Learn how RFT can be applied to issues of diversity and inclusion, and global sustainability. Finally, you’ll find a thorough discussion of how behavior analysts can use the principles outlined in this book to extend the reach of the field into a range of socially significant and critical areas for behavior change.