Ego state therapy is a therapeutic approach that views the personality as made up of distinct "ego states," or emotional “parts,” each representing different thoughts, emotions, and behaviors. These states can become conflicted or dissociated, especially after trauma. The therapy works to identify, understand, and heal these states by improving internal communication and resolving conflicts, leading to greater emotional well-being and integration.

Ego state therapy is often used for the treatment of dissociation, developmental trauma, complex PTSD and attachment disorders. It was originally developed by John G. Watkins and Helen Watkins, psychotherapists who specialized in hypnosis, dissociation, and multiple personalities.