This thesis examines the emergence and establishment of the Mackenzie clan and the Earls of Seaforth.  It details their rise to power from a relatively disadvantaged starting point as a fractured clan at the end of the 15^th century until their rise to regional dominance was capped with an earldom in the early 17^th century.  It has long been known that the clan ‘history,’ based on 17^th century writings, the mainstay of accepted Mackenzie ‘history,’ was unreliable, particularly for the sub 1500 period.  This thesis, therefore, is based as far as possible on contemporaneous source material, both printed and manuscript.  It questions not only the veracity of the earlier ‘histories,’ but also examines the motives and aims of the 17^th century writers.  The vexed question of the origins of the clan is revisited together with the nature of Mackenzie relations with Clan Donald.  The Highland policy of successive Stewart monarchs (James IV-James VI) is evaluated, together with their treatment of Ross, Àird Meadhanach and the place of the Mackenzie clan within this wider framework. The nature of clanship is also considered.  What was a Highland ‘clan’?  Some attention is paid to the structure of the clan, the establishment of cadet branches and also to the mechanisms employed for strengthening it such as endogamous and exogamous fosterage and marriage arrangements.  Clan economic initiatives are explored particularly in relation to fishing and iron working.  The Mackenzies, themselves successful planters, sought to acquire outside expertise to develop their ‘colony,’ or perhaps ‘plantation’ on Lewis.  The Mackenzies, well aware of the colonial tendencies exhibited by their Scots, English and Dutch neighbours, sought, it will be argued, to bend these groups to their own advantage while retaining ‘native’ control of these projects.  This thesis is written in Gaelic.