Gamification offers methods for influencing human behaviour that are not available with other approaches to behaviour-change interventions. Its widespread and successful use in business, education, and health care notwithstanding, it has so far not been extensively used for improving sustainability, nor have its underlying psychological principles been studied in depth. This dissertation investigates gamification with a special focus on the role of perspective taking and emotion. A gamified behaviour-change app was compared with a standard app and a webpage for its effect on participants’ sustainable behaviours. During the one month period the participants engaged with the intervention, they kept diaries about their experience with sustainability and the technology. Furthermore, the influence of dramatic elements was tested through an augmented reality approach. Gamification encourages longer engagement with the intervention, thereby influencing behaviour. Specifically, gamification increases knowledge about and willingness to invest effort into sustainable behaviours. Dramatic elements, using the power of narrative persuasion and immersion, are important aspects to consider in gamification. The theory of behavioural choice can fruitfully serve as a psychological model of how gamification affects behaviour. / Graduate