While overall extent of Irish influence on Old Norse literature is still debated, (2) there is critical agreement on importance of Irish material to Laxdola sagai' because this text offers a sustained focus on Celtic presence in Iceland. Not only does begin in Seotland, but Melkorka, daughter of King Myrkjartan of Ireland, plays a prominent role: she had been carried off in a slave raid at age 15 and eventually becomes mother of Olafr pai. These features suggest that Laxdola is the family which approaches question of Irish blood in Iceland most squarely (Sayers 1988, 97). Building off foundational comparative work of Rosemary Power and William Sayers, this article adduces a previously unnoticed Irish motif in Laxdola saga: sovereignty test for kingship, best illustrated by Old Irish Echtra Mac n Echach Muigmedoin (The Adventures of Sons of Eochaid Mugmedon), (4) earliest surviving example of a genre of medieval Irish tales that focus on sovereignty. (5) Olafr pai and his Irish counterpart, Niall Noigiallach, are both illegitimate and youngest sons who gain their fathers' inheritances at expense of their older, legitimate brothers, yet by time this motif appears in Laxdola saga, outcome and significance of sovereignty test have shifted. Awareness of these changes sheds new light on both Olafr's status in Laxdola and values at stake in his rejection of Irish kingship. In finding points of contact between Olafr and heroic biographies of Irish kings, Sayers has argued for an appreciation of Irish concept of kingship and interest in manipulating this information for thematic ends in Laxdola saga (Sayers 1989, 92), noting ways in which Olafr fails to fulfill tripartite functions of a successful sovereign (legal justice, military success, agricultural prosperity) in Irish model of kingship. Recognizing Irish roots of sovereignty test in Laxdola further aids our understanding of this work's use of Celtic motifs, as depicts Olafr successfully passing a series of sovereignty tests, yet ultimately rejecting that sovereignty itself. In what follows, I will explore parallels between Laxdola and Irish trope of sovereignty test and discuss how its themes of inheritance, leadership, and kingship have been reshaped and reframed in Icelandic milieu in saga. As Laxdola itself indicates, there were numerous avenues for oral transmission of cultural material from Celtic British Isles to ears of early medieval Icelanders. Historical and literary accounts of Iceland's foundation make clear that a significant proportion of its population, particularly its female population, came from slave raids on British Isles, (6) and recent genetic studies have confirmed that roughly 60 percent of Icelandic female settlers and 20 percent of Icelandic male settlers were of Celtic origin (Agnar Helgason, Sigrtm Siguroardottir, Gulcher, et al. 2000; Agnar Helgason, Sigrun Siguroardottir, Nicholson, et al. 2000; Agnar Helgason et al. 2001). The Viking Age Norse settlements in Ireland and rest of British Isles offer another avenue by which medieval Icelanders would have become familiar with Celtic cultural material. (7) As recent studies by Rosemary Power (1985; 2013), John D. Niles (2006), and Matthias Egeler (2013) have demonstrated, Norse (and Anglo-Saxon) texts incorporated a great deal of Celtic material that was transmitted orally before surviving manuscripts in either language were written. As Power notes, the oldest area of contact between Norse and Gaelic worlds, involving transmission of stories of kind now regarded as literature or folktale, seems to have occurred almost exclusively in Viking Age, though possibility that traditional stories that had circulated orally might have been open to supplementation by travellers' accounts in later times (i. …