*Highly anticipated, accessible, unique guide focusing on the use of language from a relational frame theory (RFT) perspective. *Creative framework for using language to elicit core client issues and promote more healthful thoughts and behaviors. *Coauthors are clinical researchers and skilled therapists; Hayes is an RFT pioneer and codeveloper of acceptance and commitment therapy. *RFT is increasingly influential, yet existing resources on the topic are impenetrable. *Perfect resource for evidence-based psychotherapists at all levels, including practitioners of CBT, acceptance and commitment therapy, and mindfulness-based therapies.