One of the most ubiquitous artifact classes observed in the archaeological record of Rapa Nui are chipped stone obsidian tools. These irregularly-shaped objects have well defined stems and are found by the thousands across the landscape. The determination of the elemental composition of obsidian tools from Rapa Nui provides information about population movement and resource acquisition. Using time-of-flight laser-ablation ICP-MS to measure compositional variability, my study characterizes source samples and a large collection of obsidian artifacts from the interior of the island. My analysis provides a look at the patterns of resource acquisition and identifies which source locations were more widely used by prehistoric Rapanui. The results presented here demonstrate that obsidian was primarily collected from one source, Orito. A secondary source, Motu Nui, was used less frequently. My data suggest that the sources of this material were not constrained by political entities and territorial boundaries but were shared by populations living across the island. Information from my study provides insight on mobility, trade, and interaction among the prehistoric populations of Rapa Nui.