This chapter discusses indigenous ecological knowledge, popularly known as traditional ecological knowledge, with a view to examining its nature and place in contributing to biodiversity conservation and/or restoration. Disciplines from anthropology and ethnobiology to systems ecology and resilience theory have demonstrated the contribution of traditional ecological knowledge to improving livelihoods, sustaining biodiversity and ecosystems services, and building resilience in social-ecological systems. A review of various ancient cultures shows how communities lived in harmony with Nature, with a tradition of reverence for the elements that constitute ecosystems, drawing their sustenance from Nature; and at the same time protecting the ancestral lands from which they were born and nurtured for millennia. Academics have popularized the concepts of consilience and transdisciplinary science, which suggest that people can achieve deeper understandings by working across the boundaries and scale limitations of individual disciplines in natural sciences and humanities.