This chapter describes the assessment phase of the standard eye movement desensitization and reprocessing (EMDR) protocol for treating posttraumatic stress disorder (PTSD). The two main purposes of the Assessment Phase are to access key aspects of the maladaptive memory network and to establish baseline measures for the level of disturbance in the target, rated with the subjective units of disturbance (SUD) scale, and the felt confidence in a positive self-appraisal, rated with the Validity of Cognition (VoC) scale. In the Assessment Phase, one identifies the image or other sensory memory, negative cognition (NC), positive cognition (PC), specific emotion, and body location of the felt disturbance. The focus of the therapeutic work in EMDR reprocessing sessions is on the reorganization of the memory network. The last step in the standard assessment phase of the selected target is identifying the location of physical sensations associated with the maladaptive memory network.