Tobacco use prevalence is particularly high in people with severe mental disorders. Such individuals also smoke more heavily, have more severe nicotine dependence, and face worse health outcomes as a result of tobacco. Although smoking is one of the most common modifiable unhealthy behaviours among people living with severe mental illness, benefits of smoking cessation programmes have not been extended to this population. There has been almost no reduction in smoking prevalence among people with SMI, even in high income countries, despite the dramatic reduction in smoking rates in the general population that has occurred during the past 40 years. The reasons for this include “diagnostic overshadowing” whereby physical health is neglected in the presence of a mental illness diagnosis; and the unsuitability of interventions designed for the general population that are predicated on high levels of cognitive function, literacy, health literacy, motivation and self-efficacy, all of which may be compromised by severe mental illness.