This article discusses how the globally-established political concept of sustainable development has become institutionalized in both decision-making and people's everyday lives in Finland over the last twenty years by focusing on "the logic of appropriateness" and how the notion of sustainable development as a utopia opens possibilities for institutional change for the future. The logic of appropriateness provides a conceptual perspective for analyzing institutions and institutional change from a normative standpoint, with a focus on culturally-shared norms and rules. This conceptual perspective is used here to illustrate and argue that notions of sustainable development have not changed cultural understandings of appropriate norms and rules that responsible decision-makers or individual citizens identify in Finnish society. The significance of sustainable development, however, cannot and should not be dismissed. After twenty years, the notion of sustainable development still creates a radical foundation for social and institutional change. As a utopia, it has potential to nurture the vagueness of appropriate rules and identifications in decision-making and people's everyday lives and to open unknown possibilities for institutional change and sustainable practices for a new future.