Through our consumption behaviour we are responsible for 72 % of the global greenhouse gas emissions. These are created by the way we live, travel, and eat and by what we buy. So far, the attempts to change people's habits by appealing to their rationale have not produced significant behaviour change. Aiming to help close the action gap between climate awareness and individual action, and to increase citizen participation in sustainability topics, the project builds a data-driven momentum for sustainable behaviour change across eight European countries. It does this by engaging citizens through a digital application to co-research, co-develop and uptake everyday life solutions for climate change, providing tools for the collection, monitoring and analysis of their environmental and consumption data. The overarching goal of PSLifeStyle is to co-create a web- and mobile-based sustainable lifestyle tool and open platform, that will enable, empower and encourage European citizens to take their personalized steps towards more sustainable lifestyles.