We have measured the elastic stress of thin films of interest in GaAs microdevice processing, particularly for GaAs micromechanical structure fabrication. Stress was determined for films deposited directly on GaAs, in contrast to previous studies examining depositions on other substrates. Stress values were evaluated from the deflection of micron-thick GaAs cantilevers. Films examined include evaporated metals, chemical-vapor-deposition silicon nitride, and sputtered indium tin oxide. Stress values obtained for our films on GaAs are compared to values for these films deposited on other substrates.