In this book, some factors affecting productivity and egg quality in brown laying hens were studied and discussed. From the study of the effect of methionine, linoleic acid and supplemented fat in the diet it could be concluded that the levels of these components of commercial diets currently used in Spain, in the last part of the production cycle, can be reduced considerably without any effect on hen productivity and little effect on egg quality. In response to the influence of calcium level and source of the diet of laying hens it could be concluded that brown egg-laying hens late in the production cycle require more than 3.5% Ca in the diet (4.08 g Ca/d) to maintain productivity and shell quality. Also, the substitution of part of the fine limestone of the diet by coarse limestone or oyster shell does not affect productive performance and tibia characteristics although it might improve some shell quality traits. Regarding the influence of main cereal and mean particle size of the cereal in the diet of laying hens it could be concluded that both corn and hard wheat can be used indistinctly in diets for laying hens when ground to pass through a 6- to 10-mm screen.