A single-frequency output power of 210 mW on the 1.3 mu m transition was obtained from a monolithic YAG laser doped with 4.2%, Nd. Lasers fabricated from high Nd-concentration YAG crystals oscillated simultaneously on the 1.319 and 1.338 mu m lines at high pump power, but in a single axial mode at both wavelengths. The oscillation frequency was continuously temperature-tunable at a rate of 3.6 GHz/degrees C over a range of 170 GHz (10 Angstrom). The emission was linearly polarized with an extinction ratio >1000:1. In two-wavelength operation, the 1.319 and 1.338 mu m transitions were orthogonally polarized.