ICD-11 Complex Posttraumatic Stress Disorder (CPTSD) is a relatively new condition; therefore, there is limited available evidence for its treatment. Prior to the recognition of CPTSD as a separate trauma condition, people who met criteria were often diagnosed with multiple co-morbid conditions such as PTSD, anxiety, depression, and emotional dysregulation difficulties. In the absence of a coherent evidence base, treatment tended to involve multiple treatments for these multiple conditions or lengthy phase-based interventions, often delivered in an integrative fashion, which was not standardized. In this paper, we present Enhanced Skills Training in Affective and Interpersonal Regulation (ESTAIR), a new flexible multi-modular approach for the treatment of CPTSD and its transdiagnostic symptoms. ESTAIR is consistent with trauma-informed and patient-centered care, which highlights the importance of patient choice in identification and sequencing in targeting CPTSD symptoms. Directions for future research are discussed.