Diode lasers offer a lightweight, rugged, and economic alternative to other types of laser source, but they often do not provide long-term stability and spectral purity of emission. We have developed a stabilized, near-infrared diode laser source that is capable of as much as 20 mW of single-mode output power for the effective replacement of a He-Ne laser in the path difference measuring system of a high-resolution (1.25-m maximum path difference) Fourier transform spectrometer. Laser characterization has been performed both in laboratory measurements and in flight tests, resulting in a relative frequency stability of better than 10(-6) on a 6-h flight.