The microstructure and chemistry of grain‐boundary phases in silicate‐doped Y₂O₃─ZrO₂ ceramics were evaluated by analytical electron microscopy. Two different silicate compositions were used: one an aluminosilicate and the other a borosilicate glass. These grain‐boundary phases had a significant impact on the grain morphology, the chemical composition of the grains, and the crystallization of second phases. These results indicate that controlled additions of specific glass phases may provide a means for tailoring the microstructure and physical properties of zirconia ceramics.