Little information is available on the prevalence and determinants of lifestyle related risk factors for poor health (obesity, poor diet, physical inactivity, smoking and alcohol abuse) among people with intellectual disabilities. This study reports the prevalence of these risk factors for 500 people with intellectual disabilities living in different forms of residential provision in the UK. Variables which predict the presence of these risk factors are also identified. While levels of smoking and alcohol abuse were low, the prevalence of poor diet, obesity in women and physical inactivity was high. Analyses of predictors of risk factors present a mixed pattern with regard to participant and service characteristics, with greater ability and less restrictive residential settings being associated with poor diet, smoking and obesity, but physical inactivity being associated with lower ability and more restrictive settings. It is argued that increasing levels of moderate or vigorous physical activity among people with intellectual disabilities would be the single most effective way of improving the health of people with intellectual disabilities.