Complex trauma is prevalent in the general therapy population and is rooted in early neglect, and traumas of long duration, resulting in posttraumatic stress disorder (PTSD), dissociative disorders, attachment problems, and personality disorders. This chapter provides information that will help Eye Movement Desensitization and Reprocessing (EMDR) therapists enhance their ability to provide effective EMDR treatment for clients diagnosed with complex trauma who are also dealing with current health problems. It highlights the use of the adverse childhood experiences (ACE) questionnaire, which provides much needed information on childhood abuse, neglect, attachment disorders, PTSD, and dissociation. This questionnaire, when combined with a broad developmental and health history, will be very helpful in case conceptualization and development of targets for work in phases 4 to 7. Additionally, the chapter describes the links between the ACE issues and later health risks and problems that make these clients difficult to treat.