The paper discusses the 'value-through-utility' argument as a key ingredient of environmental educators' interests in traditional ecological knowledge (TEK), and examines some of the epistemological and philosophical tensions it generates in employing TEK within the context of learning with sustainability in mind. In an earlier article (Reid et al., 2002), we argued that it is important to recognize that it is outsiders rather than insiders who usually conceptualize TEK. In this paper, we develop this point further, exploring the theorization and practice of TEK-based environmental education in the context of discourses about sustainability and environmental education.