The aim of the study was to investigate negative and positive changes in individuals who experienced psychological trauma; specifically it is interested in protective factors for posttraumatic stress disorder (PTSD) and in factors that facilitate posttraumatic growth (PTG), a positive transformation following a traumatic event. The participants were 434 University of Southampton students and staff. The study used a cross-sectional design. Participants completed an online survey which assessed demographic characteristics, information about trauma and PTSD, depression and anxiety, posttraumatic cognitions, attachment, posttraumatic growth, self-concept clarity, and self-esteem. Multiple linear hierarchical regression revealed that PTSD severity is multiply predicted by subjective severity of traumatic event, number of early traumas, both anxiety and avoidance dimension of attachment, self-esteem, posttraumatic cognitions, and depression. In addition, it was found that the negative self-view (as measured by the PTCI) partially mediates the relationship between attachment styles and PTSD, self-esteem and PTSD, and number of early traumas and PTSD. Surprisingly, it was revealed that only PTSD severity, and demographic variables significantly predict PTG in the final model. The research support the assumption that vulnerability factors may be related to psychopathology after a traumatic event. It showed that individuals who have experienced early traumatic events, are insecurely attached, and have low self-esteem report higher amounts of negative post-trauma cognitions and PTSD. The role of insecure attachment and low self-esteem for PTSD may have important therapeutical implications and should be included in assessment and formulation.