Microblades were a common feature of many lithic toolkits around the North Pacific during the late Pleistocene and early Holocene epochs. On Haida Gwaii, on British Columbia's North Coast, the earliest known microblades have been recovered from the Richardson Island site and date to approximately 8750 BP. Deep, well-defined stratigraphy at the site has provided a unique opportunity to observe a major technological shift as, between 8750 BP and 8500 BP, microblades gradually replaced the earlier bifacial toolkit and came to be a definitive aspect of the subsequent Moresby tradition technological suite. Several hypotheses have been presented, including microblades as a response to increasing raw material scarcity as a result of sea-level change, microblades as a technology imported by incoming Athapaskan speaking peoples, and microblades as an in situ design response to new subsistence practices brought about by ecological changes following the end of the last glaciation: a more durable, more deadly weapon well adapted to high-risk hunting activities. In this thesis I examine the possible reasons behind that shift in lithic technology. My analysis employs multiple lines of evidence to consider the theories. I examine the microblade assemblage and consider aspects of tool manufacture, use, and discard to determine how the microblades may have been used, and how they may relate to other microblade traditions in the region; I consider the paleoecology of southern Haida Gwaii during the early Holocene; and I use a set of controlled experiments to compare bifaces and slotted points in terms of durability and wound channel creation. / Graduate