Schizophrenia is a common and serious psychiatric illness  affecting 0.5–1% of the population in early adulthood. Despite continuing progress, current treatments continue to have significant side effects and inconsistent efficacy across patients. The disease remains incurable, with the best outcome being the control of symptoms and preservation of sufficient functionality and independence. Schizophrenia is a disease with remarkable phenotypic heterogeneity. The symptoms are generally divided into three categories. Positive symptoms, with which the general public is most familiar, include hallucinations and delusions of varying content, and are perhaps the most disruptive. Negative symptoms include lack of motivation, anhedonia, and flat affect. Cognitive symptoms such as defects in attention, concentration, working memory, and critical thinking are the most incapacitating, leading to significant disability. Each patient can have a different mix of the three types of symptoms leading to an overall highly heterogeneous phenotype. Affective symptoms may combine with the classic symptoms of schizophrenia leading to schizoaffective disorder, which some genetic researchers categorize with schizophrenia and others with bipolar disorder (BD). Heterogeneity also manifests in the patients’ response to medication, frequently resulting in multiple changes in treatment strategy during the course of the illness as patients navigate through ineffective treatments. It is clear that schizophrenic patients would benefit considerably from a robust prediction of their response through individualized medicine. A good understanding of the underlying genetics, the importance of environmental factors and the interaction of the two, along with careful clinical characterization may achieve that in the not so distant future.