Psychogenic non-epileptic seizures (PNES) are one of the most common differential diagnoses of epilepsy. PNES are poorly understood and often sub-optimally treated. This article summarizes current knowledge about the etiology of PNES. Through describing the interactions of predisposing, precipitating, perpetuating, and triggering factors, an integrated biopsychosocial model of a complex disorder is developed. PNES emerge as a dissociative response to a range of different stressors in vulnerable individuals. Once established, maintaining factors turn a temporary disturbance into a chronically disabling disorder.