1. Growth reponses of Red Kidney bean and cotton seedlings resulting from gibberellic acid (GA) and 2,4-dichlorophenoxyacetic acid (2,4-D) interaction were studied following foliar application of these growth substances. 2. In amounts greater than 1 μg. per plant, 2,4-D inhibited GA-induced shoot elongation; this inhibition was proportional to 2,4-D dosage. With 5-10 μg. of 2,4-D the terminal bud developed into a mass of yellow proliferated tissue. A second shoot developing in the axil of the deformed bud exhibited the extreme elongation of the GA-treated control plants. The effectiveness of GA persisted for at least 3 weeks. 3. When lower dosages of 2,4-D were used (1 μg. or less), the two compounds acted synergistically and promoted shoot elongation of cotton seedlings and petiole elongation of bean leaves. 4. The deforming effect of 2,4-D on the leaves of bean and cotton with dosages as low as 0.1 μg. was not affected by GA in amounts as great as 200 μg. per plant. 5. GA promoted the bean epicotyl curvature which develops as a result of 2,4-D action on cell elongation.