Based on the indeterminate character of the sustainability concept, a procedural and discursive understanding of sustainability decision making and corresponding approaches for education for sustainability (EFS) is proposed. A set of criteria for teaching strategies to promote sustainability decision making, taking into account the demands of deliberative democracy theory, are presented. These criteria (such as reason, complexity management, critical thinking, etc.) are used to argue for an educational approach that involves the development, justification, and weighting of arguments in combination with an instructional tool called Target-Mat. According to a consequent process orientation, structures for arguing or defining sustainability are not given as authorized standards. Suggestions from previous social discourse are only introduced as controversial pairings—for example, different definitions of sustainability. Examples of student decision-making processes are given to demonstrate the potential of the approach to encourage student reflection and cooperative negotiation that engenders a successive deepening of their argumentation