Investigations were conducted in 1966 and 1967 at Tucson, Ariz., to study some effects of soil‐moisture stress, at three different stages of development (jointing, flowering, and dough) on the growth and grain yield of spring wheat (Triticum aestivum L. em Thell.) planted in December. A critical period in the growth of wheat was the jointing stage for moisture. Stressing wheat for water at jointing resulted in fewer days from planting to flowering, shorter plants, more lodging, lower grain yield, lower grain volume‐weight, fewer heads per unit area, and fewer seeds per head. Soil‐moisture stress at any stage of growth decreased grain yield. When wheat was stressed at jointing, reduced grain yield resulted from fewer heads per unit area and fewer seeds per head. However, when moisture stress occurred at the flowering and dough stages, lower grain yields were caused by lighter seed‐weight. Stress at the flowering and dough stages also hastened maturity.