Cannabis use has often been associated with various forms of psychosis. Today it is well established that everyone produces marijuana-like compounds known as endocannabinoids. The endocannabinoid system is a homeostatic regulator of all body systems including the nervous system. As a result, imbalances in the endocannabinoid system have been considered as possible causes of various forms of mental illness and abnormal behavior. In this paper, a novel hypothesis is presented that suggests that an as yet undefined subset of schizophrenia is caused by an excess of endocannabinoids that are produced to protect the brain in response to infections by agents such as Toxoplasma gondii.