The egg is a fragile commodity and the industry suffers enormous economic losses from breakages. The need to define and improve eggshell quality and quality control methods has never been greater. Using electron micrographs, colour photos and succinct practical text, the author describes the anatomy and physiology of egg and eggshell formation, covering age, environment, nutrition and disease. Eggshell strength is discussed with reference to breakage and infection problems. The commercial importance of eggshell appearance, colour and texture is also covered as are techniques for assessing egg and eggshell quality.