This theoretical paper clarifies the concept of sustainability learning and specifically analyzes motivational aspects. Mastering the challenges of sustainability requires individual learning as well as learning processes on different levels of human systems ranging from groups and organizations to human societies, and mankind as a whole. Learning processes of individuals play a fundamental role, since individuals constitute and shape the larger social aggregates. Learning processes on the level of social aggregates are important since social systems embed and influence individuals. Therefore, sustainability learning needs to be understood as a multi-level concept, comprising individual learning as well as learning processes of human systems. Transdisciplinarity and mutual learning between science and society are considered fundamental approaches of sustainability learning, and hence increase the capacity of mankind to manage human-environment systems in sustainable ways. Based on systemic considerations, the two-fold role, in which motivations act as determinants and targeted outcomes of sustainability learning processes, is explained together with the outstanding role that cooperation, hence cooperative motivation, plays for sustainable development. Finally, the multifaceted, controversial discourses on what sustainability ultimately means (for the scientific community, for a given cultural or political entity, organization, or individual person) are considered.