Dissociation is a normal life adaptation that can become pronounced and disruptive in the setting of repeated or extreme exposure to trauma. Children and adolescents may experience dissociation due to a trauma or stressor-related disorder, anxiety, or depressive disorders. Children and adolescents also may mimic behavior they see online as a way of expressing internally painful and intolerable experiences. Myth and misinformation surround the diagnosis of dissociative identity disorder (DID), formerly multiple personality disorder. The purpose of this article is to provide school nurses with evidence-based information on DID and resources for practice regarding how to provide a secure, consistent approach to students who are being traumatized, misunderstood, or excluded at home or at school. Part 1 of this two-part series describes DID foundations and DID in school-aged children, reviews controversy spurred by social media representation, and presents the Trauma-Informed Care (TIC) model. TIC offers useful perspectives regardless of a student’s presentation or diagnostic status. Part 2 will discuss recommendations for managing dissociative presentations using a team-based approach, focusing on the school nurse’s roles and responsibilities.