The effects of plant nutrients on citrus fruit quality cannot be considered independently of their effects on yield. In some cases quality can be improved by sacrificing some yield;however, from the overall economic point of view, it is usually advantageous to sustain maximum fruit yield even though there may be some sacrifice in fruit quality. This report emphasizes the nutrient effects on quality in the ranges in which we expect maximum yield to be sustained. If the deficient ranges for yield are included, the degree of effects on quality is greater. The nutrient ranges and effects discussed are primarily those encountered by the authors under California conditions.