Behavioural science has identified several interventions that increase the likelihood of sustainable choices. For example, putting a vegetarian product on a visible in-store location enhances sales of that product. In this project I look at when and how effects of a behavioural intervention in a specific purchase context spills over to consecutive purchase decisions. I demonstrate that the direction of the spillover effect is critically dependent upon conscious vs. nonconscious goal pursuit and goal importance. First I demonstrate that people who attach higher importance to a pro-environmental goal will display more positive spillover behaviour in case of conscious (vs. nonconscious) goal pursuit while lower importance people will display negative spillover behaviour in case of conscious and nonconscious goal pursuit. I explain this by reinforcement of self-perception and licensing both taking place in case of conscious goal pursuit contingent on pro-environmental goal importance. Second, I demonstrate the potential of different types of behavioural interventions to evoke nonconscious and conscious goal pursuit, also as a function of pro-environmental goal importance. This research has theoretical implications for consecutive goal-directed behaviour inside/outside the sustainability domain as well as managerial implications as the presence of positive and negative spillover behaviour has a huge impact on the net effects and cost efficiency of behavioural interventions.