Lima bean.is one of the important vegetable crops in most of the countries where it is grown, including the United States of America. This crop is harvested for its green beans, which can also be processed, or allowed to mature as "dry beans." The practice of growing lima beans !or processing has indicated that quality and yield are influenced by many factors, among which the stage of maturity at time of harvest is possibly the most important. Lima beans continue to increase in size until fully matured, but most processors agree th.at the green beans attain maximum quality prior to that stage, after which the yield increases while the quality decreases. In actual practice, harvesting should occur at the time the greatest yield of acceptable quality could be obtained. Maturity is thus an extremely important factor to processors interested in satisfying the consumer's demand !or high quality. The canning trade (16) still has no further measurements !or grading the quality of raw lima beans than the visual test, which depends upon the flavor, texture, and freedom from defects. It would seem, therefore, th.at more exact information is needed on the relationship of maturity to edible quality in lima beans. In studies with other vegetables it has been shown that certain chemical and physiological changes are involved as the crop matures. Pollard, Wilcox, and Peterson (5) found with peas that the starch content increased as the peas advanced in maturity, while ascorbic acid content decreased with maturity. Henry, Wilcox, Pollard, and Lindquist (15) found that in sweet corn the total and reducing sugars decreased as sweet corn advanced in maturity while the total solids and alcohol insoluble solids increased. These changes often influence quality adversely. To determine more fully the factors affecting the relationship of stage of maturity and quality in lima beans, this experiment was conducted in 1953 at the Farmington Field Station of the Utah Agricultural Experiment Station.