This chapter examines the types and prevalence of psychotic symptoms and disorders in older adults, and offers insight into distinguishing between the disorders and guidelines for treatment. Psychotic disorders are very common (lifetime prevalence 25%) with risk increasing with age. Prevalence rates have ranged from 1-13.4%. Psychotic disorders can be divided into “primary” (40%), due to the direct effect of a psychiatric disorder and “secondary” (60%), caused by a non-psychiatric condition. Dementia is the most common cause of psychoses. The mnemonic “6 Ds” can be used to remember the principal causes of psychotic disorders: Disease, Delirium, Drugs, Dementia, Depression and mania, and Delusions and schizophrenia spectrum disorders. There are no pathognomonic signs to differentiate psychosis caused by psychiatric illness from that caused by another condition, although there are some characteristics that may serve to distinguish them. There are few controlled treatment studies and most guidelines have been developed through expert consensus panels. It is recommended that psychosocial interventions should be tried initially and medication should be used only when the former has failed or when symptoms present a danger to the patient or caregiver.