Before we answer the question how environmental social sciences contribute to the research about grand challenges, we ask: what are environmental social sciences? What disciplines belong to them and what type of research is done? We then elaborate the role of environmental social sciences, and particularly political science, in the inter- and trans-disciplinary context. We wonder, what is a natural, what a societal problem, and where the study of social-ecological interactions seems most appropriate. I will present some highlights out of social scientific research about the environment and conclude about some thoughts related to the science-policy and science-practice interfaces.