This chapter describes the third of the eight phases, the Assessment Phase of Eye Movement Desensitization and Reprocessing (EMDR) therapy that is related to the developmental stages of children from infant to adolescent. It explains the procedural steps with detailed explanations of the techniques and skills necessary for successfully steering a child or teenager. It is essential for the therapist to recognize that eliciting the procedural steps for the phase is impacted by the child/teen’s level of development, and scripts for the procedural steps need to be adjusted into child/teen language. The chapter provides instructions to the therapist with scripts for each of the procedural steps. The assessment phase starts with Target Identification and Organization, which is a continuation of Phase 1 and the therapist continues with image, Negative Cognition (NC) and Positive Cognition (PC), Validity of Cognition (VoC), emotion, Subjective Units of Disturbance (SUD), and body sensation.