This article reviews the complexity of adaptation and symptomatology in adult survivors of childhood neglect and abuse who meet criteria for the proposed diagnosis of Complex Posttraumatic Stress Disorder (Complex PTSD), also known as Disorders of Extreme Stress, Not Otherwise Specified (DESNOS). A specific EMDR protocol, Resource Development and Installation (RDI), is proposed as an effective intervention in the initial stabilization phase of treatment with Complex PTSD/DESNOS. Descriptive psychometric and behavioral outcome measures from two single case studies are presented which appear to support the use of RDI. Suggestions are offered for future treatment outcome research with this challenging population. © 2002 Wiley Periodicals, Inc. J Clin Psychol 58: 1465–1487, 2002.