Self-identity is a flexible and linear/non-linear dynamic system that consists of various identities and hierarchical sub-modules and operating processes and develops (grows or declines) through dealing with stressors and traumas (IST). ISTs may threaten the existence, the maintenance or development of one of the persons' identities. Different IST types include personal identity, physical identity, role identity, and social identity stressors/traumas and constitute a multi-level hierarchy. A value processing system, related selfevaluation, and core developmental assets are identity-impeded operational processes in each identity. The salience of one identity may be activated by IST and became the situational (or the default) lens that biases the person's appraisal and coping response. The most traumatizing ISTs are those that threaten identities' existence, triggering existential anxieties. The macro dynamics of accumulation, proliferation and the interaction between pre-identity, identity, and post-identity traumas determine their mental health impact, rather than a triggering trauma.