To evaluate the influence of gibberellin on citrus fruit development and quality—and other tree responses—Thompson Improved Navel Oranges were treated with potassium gibberellate during the first week of November 1957. Oranges 2.5?-2.6? in diameter were individually-dipped along with four subtending leaves in the treatment solutions. Concentrations of technical gibberellin—containing approximately 82% potassium gibberellate—used were 500, 1,000, and 2,000 ppm—parts per million. A non-ionic wetting agent was added at 0.05%. Oranges which served as controls were selected for size but were not treated. A randomized complete block design with eight replications was used. Each plot consisted of three trees with 17 test oranges on each.