This paper examines the influence of SiO2 doping on densification and microstructure evolution in Nd3xY3-3xAl5O12 (Nd:YAG) ceramics. Nd:YAG powders were doped with 0.035-0.28 wt% SiO2 and vacuum sintered between 1484 degrees and 1750 degrees C. Si-29 magic-angle spinning nuclear magnetic resonance showed that Si4+ substitutes onto tetrahedrally coordinated Al3+ sites. High-resolution transmission electron microscopy showed no grain boundary second phases for all silica levels in samples sintered at 1600 degrees-1750 degrees C. Coarsening was limited by a solute drag mechanism as suggested by cubic grain growth kinetics and transmission electron microscopy energy-dispersive X-ray spectroscopy observations of increased Nd3+ concentration near grain boundaries. Increasing SiO2 content increased both densification and grain growth rate and led to increasingly coarsening-dominated sintering trajectories. Fine-grained (<3 mu m), highly transparent (>82% real in-line transmission) ceramics were produced by sintering 0.035 wt% SiO2-doped ceramics at 1750 degrees C for 8 h. Coarse-grained (18 mu m), transparent samples were obtained with 0.28 wt% SiO2-doped Nd: YAG when sintered at 1600 degrees C for 8 h.