The traditional ecological knowledge (TEK) of local and indigenous people supports the resilience of social-ecological systems and is an important aspect of global biocultural diversity. However, TEK is at risk of erosion amid social and ecological change, and may be threatened by homogenising influences such as formal school systems. Loss of TEK is of particular concern in countries such as Vanuatu, a culturally diverse nation where TEK is a critical component of resource management, medicinal practice, and adaptive capacity. This thesis aims to fill four key literature gaps surrounding the variation, transmission, and maintenance of TEK, and is situated in four rural communities on Malekula Island, Vanuatu. This research employs an interdisciplinary mixed-methods approach across four core chapters. The first uses multi-model inferencing to show that systems of TEK are dynamic and complex, and that change is variable across domains of knowledge and segments of the population. Data in this chapter indicate that ethnomedical knowledge is at risk of erosion in younger age cohorts. The second core chapter shows that the cultural transmission of TEK is predominantly vertical in nature (i.e. passed from parent to child), is initiated during the early teens, and that some skills (such as the carving of ceremonial items) appear to be less salient to younger age cohorts. This chapter also notes a changing developmental niche for TEK transmission, and suggests that changes in both the setting and strategies for knowledge transmission are key mechanisms that drive TEK variation. The third and fourth core chapters discuss aspects of TEK maintenance: first, by examining top-down strategies for TEK revitalisation by eliciting local perceptions of the value of TEK to formal school systems; and second, by identifying the triggers and barriers to bottom-up, in situ TEK maintenance in local organisations known as „kastom schools?. Both approaches have potential to conserve aspects of TEK, however in situ approaches may be best for encouraging the maintenance of knowledge and practice within an appropriate cultural context. There are, however, significant epistemological barriers to both top-down and bottom-up approaches to TEK maintenance, which may ultimately limit their effectiveness.