Thermal stresses induced in a flat, rectangular, 75S-T6 aluminum-alloy plate by nonuniform heating are determined both experimentally and theoretically. The characteristics of commercially available bonded resistance wire strain gages are first investigated to determine their suitability for measuring stresses under simple conditions of stress and temperature. The gages are then used to measure thermal stresses in the flat plate in order to study their suitability under more complicated conditions. The experimental results are found to be in satisfactory agreement (within plus or minus 5 percent of maximum calculated stress) with an approximate theoretical solution of the problem.