In this study, Lev Vygotsky's (1978) Zone of Proximal Development (ZPD) provides inspiration for a teaching approach for sustainability in a social science discipline, where students often lack or have widely varied levels of foundational understanding. This qualitative case study describes intellectual processes and aspects of the educational experience of student participants experiencing such an approach. This study suggests that this approach is useful for filling gaps in understanding about this inherently complex concept while maintaining student engagement, useful in disciplines where the integration of sustainability is slow or in transition.