What Coolness is omnipresent in our daily lives. Yet, we know almost nothing about what coolness is, how it is created or lost, and its impacts on our behavior. Yet, it is important: Companies, people and cities want to be cool but have no idea how to become cool. The aim of this project is to make coolness a domain of research. I aim to investigate what coolness actually is, what makes a cool city or brand or person, and how coolness perceptions shape sustainable behavior. I will develop a global coolness ranking and make coolness an actual research subject, with far-reaching implications for academia, business and society. Coolness is omnipresent in our daily lives, hence it should also be researched. Why Notwithstanding the importance of coolness and the omnipresence of the expression 'cool' in our everyday lives, we know almost nothing about what coolness actually is and how it can be created. The question of what makes a cool city (or brand or person), and how coolness perceptions impact behavior remains unanswered. While coolness is a quality desired by many, it is not understood in academia and very few managers have an idea of how to make their offering cool. In conclusion: While we talk about coolness in our daily lives, research is remarkably silent on this important topic. Addressing and closing this big gap is my motivation for this project. How This research investigates coolness in two complementary sub-projects (SP). SP 1 investigates what coolness is and develops the global coolness ranking: The first of its kind ranking that measures coolness of the top 100 cities, 100 brands and 100 people. It uses a mixed-methods approach consisting of a) a systematic literature review, b) exploratory in-depth interviews with consumers, and c) quantitative, quasi-experimental conjoint analyses. SP 2 examines the art of crafting coolness and researches its various important roles in business and society, such as its role in company performance and political elections. It is further researched over time and across cultures, using both historical data and quasi-experimental designs. SSR People are particularly attracted toward behaviors that are considered as cool (and make them look cool). Hence, a huge, yet to be exploited potential, is to craft and communicate 'cool' socially desirable behaviors (e.g., responsible consumption, saving water, actively endorse equality and diversity). This project sets out to examine the buildings blocks of cool, and can thus have a strong impact on addressing society's sustainable development goals (SDG's) by crafting cool and sustainable behaviors. Specifically, it is argued that contemporary societal emphasis on sustainability and equality can be attributed, at least in parts, to considerations of coolness. The current project takes its point of departure in this notion to foster cool and sustainable behavior.