Smoking is the single most preventable cause of premature mortality for people with serious mental ill health (SMI). Yet little is known about the reasons why service users smoke or what their motivations for quitting might be. The aim of this paper is to explore smoking behaviours, reasons for smoking and motivations for cutting down/stopping smoking in individuals with SMI who expressed an interest in cutting down or stopping smoking. Prior to randomization, the smoking behaviours and motivations for wanting to cut down or stop smoking of participants in a randomized trial were systematically assessed. Participant's primary reasons for continuing to smoke were that they believed it helped them to cope with stress, to relax and relieve boredom. Participant's main motivations for wanting to cut down or stop smoking were related to concerns for their own health. Previous attempts to stop smoking had often been made alone without access to evidence supported smoking cessation therapy. Future recommendations include helping people with SMI to increase their activity levels to relieve boredom and inspire confidence in their ability to stop smoking and challenging beliefs that smoking aids relaxation and relieves stress.