Objective Complex post-traumatic stress disorder (CPTSD) will be introduced in ICD-11 and comprises symptoms of PTSD and disturbances in self-organisation (DSO). The association of trauma with PTSD and DSO is not yet fully understood. We investigated the path from child maltreatment to PTSD and DSO and examined the mediating role of emotion regulation (ER) and adult interpersonal re-victimisation. Method Adult patients (N = 193) from a Scottish National Health Service clinic participated in the project. Participants completed measures of life events, ICD-11 PTSD and CPTSD, and ER. Path analysis was used to assess possible direct and indirect effects from childhood trauma on current post-traumatic psychopathology. Results Overall results indicate that the path from child maltreatment to PTSD is a direct one, while the path to DSO is indirectly mediated by ER. Conclusions Future research should address the potentially beneficial effect of treatment protocols for CPTSD explicitly aiming at reducing ER difficulties.