The Functional Analytic Psychotherapy Rating Scale (FAPRS) is behavioral coding system designed to capture those essential client and therapist behaviors that occur during Functional Analytic Psychotherapy (FAP). The FAPRS manual presents the purpose and rules for documenting essential aspects of FAP. The FAPRS codes are exclusive and exhaustive for FAP essential behaviors but also include codes for generally effective therapy behaviors by both client and therapist. Client behaviors identified include those that are FAP-specific such as Clinically Relevant Behaviors (in-session improvements and problems), specification of controlling variables, and discussion of outside problems and improvements that have been identified as targeted behaviors. Therapist behaviors that have been identified as theoretically essential for conducing FAP are included such as discussions about the therapeutic relationship, responding effectively and ineffectively to in-session client behaviors, and evoking client behavior in-session. For each behavioral code a definition is provided along with examples and counter examples of how the code might be applied to client or therapist behaviors. A decision hierarchy is provided for those cases when a client or therapist behavioral event (called a turn) may receive more than one possible code. The FAPRS can be used as a tool in research (e.g., to provide evidence for the proposed mechanism of change for FAP) or as a method for assisting the training of psychotherapists. The FAPRS has demonstrated acceptable psychometric properties (demonstrated by Callaghan, Follette, Ruckstuhl, & Linnerooth, this issue).