Tobacco smoking during pregnancy represents a serious health risk and cessation has huge benefits both for mothers and their children. Pharmacotherapy and behavioural support are effective to aid smoking cessation in the general population but have limited success in pregnancy. To improve behavioural treatment approaches for pregnant smokers, it would require novel targets for interventions and alternative modalities through which these programmes are delivered. Smartphones offer the potential for delivering behavioural support in a way that could be popular among pregnant smokers, and ‘identity change’ has been proposed a potentially useful target for smoking cessation interventions. This talk will discuss the development of SmokeFree Baby, a smartphone application for pregnant smokers, and describe the ways in which both qualitative and quantitative studies informed the content and design of the intervention that, among other key components, harnesses identity change as behaviour change technique to promote cessation in pregnant smokers. Ildiko Tombor’s PhD is funded by the Society for the Study of Addiction and the National Centre for Smoking Cessation and Training provided further funding for the app development.