The present thesis analyses the recognition and realisation of the international legal, human and the inherent right of Indigenous Peoples to exercise internal self-determination through effective self-governance within the nation-states of Canada and New Zealand. The following areas are reviewed in depth: first, internal self-determination which is, inter alia, about international fora and national governments recognising this fundamental right of Indigenous Peoples to self-govern as nations within; second, effective self-government which is, inter alia, about Indigenous Peoples having the authority and capability to govern themselves; and third, authentic representation which is, inter alia, a manifestation of internal self-determination and effective self-government at the indigenous local, regional and national operational levels. The challenges and issues that emerge at all levels, that is, between governments and indigenous entities, and within indigenous communities themselves, are examined extensively. The thesis findings highlight that the frequency and complexity of these challenges, as well as the inadequate and inappropriate fora and processes for resolution offered, make it incredibly difficult for Indigenous Peoples to recognise, realise and actualise the government of themselves.