The power scaling and frequency stabilization of a high-power, injection-locked, arc-lamp-pumped Nd:YAG laser at 1064 nm are discussed theoretically and experimentally. Thermal lensing and induced birefringence at high pump powers are modeled, and the effectiveness of the model for compensating thermal lensing is demonstrated with four different laser heads. Two distinct active frequency-stabilization schemes for injection-locked lasers are also compared theoretically and experimentally. These efforts yield a 24-W, linearly polarized, continuous-wave, TEM00 output with a spectral linewidth of 1.5 Hz measured by heterodyne detection.