A continuous-wave, diode-pumped, room-temperature Tm:YAlO3 laser was built, characterized, and compared with a theoretical model. Spectroscopic parameters of the laser crystal, such as the pump band ((3)H4 manifold) lifetime, the upper laser level ((3)F4 manifold) lifetime, and the absorption coefficient were measured. The experimental data were used to calculate the quantum efficiency of Tm self-quenching of the (3)H4 manifold.