The increased awareness of the exploitation of resources, as well as the negative ecological consequences of the modern way of life, has made sustainability a central guiding concept of social change in the 21st century. Sustainability has taken the form of a largely undisputed normative model of development, behind which, however, very different conceptions of the future are concealed: from the attempt to initiate a major socio-ecological transformation, through modernization processes, to control practices in a state of emergency. This special issue aims at these practices but is not primarily concerned with sustainability as a normative guiding idea that can just be pursued. However, a sociology of sustainability has to ask which conflictual spaces of possibility for socioeconomic change open up when very different ideas of a sustainable future are in conflict with each other. Three ideal-typical trajectories or futures of sustainability emerge, which can be theoretically grasped with the terms modernization, transformation and control. These three concepts of a sustainable future can also be found in the ambivalent imaginations, practices and structures of various constellations of actors.