Abstract: This dissertation undertook to investigate the social and religious dynamic at play in processes of religious conversion within two cultures, the Sami and the Scandinavian (Norse). More specifically, it examined some particular forces bearing upon this process, forces originating from within the cultures in question, working, it is argued, to dispute, disrupt and thereby counteract the pressures placed upon these indigenous communities by the missionary campaigns each was subjected to. The two spheres of dispute or ambivalence towards the abandonment of indigenous religion and the adoption of the religion of the colonial institution (the Church) which were examined were: economic activity perceived as unsustainable without the 'safety net' of having recourse to appeal to supernatural powers to intervene when the economic affairs of the community suffered crisis; and the inheritance of ancestral tradition. Within the indigenous religious tradition of the Sami communities selected as comparanda for the purposes of the study, ancestral tradition was embodied, articulated and transmitted by particular supernatural entities, personal guardian spirits. Intervention in economic affairs fell within the remit of these spirits, along with others, which may be characterized as guardian spirits of localities, and guardian spirits of particular groups of game animals (such as wild reindeer, fish). These same roles and functions may have been assigned to guardian spirits within the religious conceptions of Scandinavian communities, and an attempt was made to demonstrate that this was at least partially the case. Personal guardian spirits were certainly heritable in both cultures; to accept and receive them as inheritance was an act and an event which expressed and demonstrated an individual's place within a family (either as blood relative or in-law, or sometimes friend) and the body of tradition which that family possessed and enacted. In both cultures these spirits were key constituents of the web of indigenous religious conceptions, and central cogs in the machine of relations with the supernatural sphere; as such they represented and embodied the primus motor of 'paganism' in the eyes of missionaries, and were accordingly demonized and targeted for some of the most vehement bile directed by the Church against the indigenous religion. Other themes, both broader and narrower, addressed or touched upon in the present study include: continuity and discontinuity of religious customs in the conversion and post-conversion eras; contextualization of religious and magical rituals within the immediate social, ecological and economic circumstances to which the community which had recourse to said rituals was subject; Christian attitudes to inherited cultural traditions, encompassing revisionism, rehabilitation of 'pagan' ancestors, the concept of the 'noble heathen', the de-sacralizing of 'pagan' cosmology and its preservation for posterity; indigenous religious discourse, and specifically that placed into the mouths of (or articulated by) personal guardian spirits, as an expression and externalization of the experience of conversion and the behaviour, tone and rhetoric of missionaries and missionary kings; folk religiosity as social and political dissidence contra the alliance of state and orthodox religion; and more generally the humanspirit contract and partnership and the dynamic pertaining within it.