Bipolar disorder is a complex, recurrent, and severe mental illness that has an onset typically between 13 and 30 years of age and a lifetime prevalence of 1.4%.1 It is characterised by episodes of mania or hypomania with elation, overactivity, and disinhibited behaviour, as well as episodes of depression with profound loss of interest and motivation, often with milder depressed mood in between episodes. Bipolar disorder is associated with an increased risk of suicide and physical illness, such as ischaemic heart disease, diabetes, chronic obstructive airways disease, pneumonia, and unintentional injury.2 Around two thirds of people with bipolar disorder also experience another mental disorder, usually anxiety disorders, substance misuse disorders, or impulse control disorders.1 The risk of recurrence in the year after a mood episode is especially high (50% in one year and >70% at four years) compared with other psychiatric disorders,3 and this has important implications for the long term management of the disorder. This article summarises the most recent recommendations from the National Institute for Health and Care Excellence (NICE) on assessing and managing bipolar disorder in adults, children, and young people.4 NICE recommendations are based on systematic reviews of the best available evidence and explicit consideration of cost effectiveness. When minimal evidence is available, recommendations are based on the Guideline Development Group’s experience and opinion of what constitutes good practice. Evidence levels for the recommendations are given in italic in square brackets. ### Care for adults, children, and young people across all phases of bipolar disorder