A dual-beam focused ion beam scanning electron microscope was used to collect a series of parallel electron backscatter diffraction maps of polycrystalline yttria. Using characteristics of the triple junctions, the individual layers were aligned and the geometries of the grain-boundary planes between the layers were determined. This information was used to calculate the five-parameter grain-boundary character distribution (GBCD) and grain-boundary energy distribution (GBED). The GBCD derived from the three-dimensional data was qualitatively the same as that derived from a stereological analysis of the same data. The anisotropy in the GBCD of yttria is relatively weak compared with other ceramics and is inversely correlated to the GBED.