Six experiments were conducted to investigate the effect of dietary composition on the folacin requirement of broiler chicks and to determine the folacin requirement of growing Japanese quail. The folacin requirement of both chicks and quail could not be determined when an isolated soybean protein based diet containing 0.44 mg. folacin per kilogram was used. Dietary composition affects folacin requirement of growing broiler chicks. Three values for the folacin requirement of growing broiler chicks were determined when three different basal diets were fed. With a low-glycine, casein based diet, growth was limited more by glycine than folic acid which improved growth only at 1.69 mg./kg. When 0.7% glycine was added to this casein diet, the folacin requirement was determined to be between 0.34 and 0.49 mg./kg. diet. However, with a casein-gelatin based diet, the folacin requirement was found to be between 0.12 and 0.27 mg./kg diet. Folacin deficiency in growing Japanese quail caused poor feathering, high mortality, leg weakness and cervical paralysis. A curly-toe system was observed in coturnix chicks fed low levels of folacin and might also be a consequence of folacin deficiency. The folacin requirement of growing Japanese quail was found to be 0.30 to 0.36 mg./kg. diet when a casein-gelatin based diet was fed.