Carboxymethyl cellulose (CMC) is the most widely used co-binder and rheology modifier in paper coating. This work presents an investigation on the effects of CMC on coating structure development by measuring viscosity of the coating colors and by characterizing properties of the dried coatings. The results showed that CMC addition increased coating color viscosity and impeded latex migration to the surface during drying. However brightness, porosity and K&N ink absorbency of the coatings increased. It was assumed that viscosity increase and colloidal interactions between CMC and pigment particles caused less latex to migrate to the surface during drying, which in turn results in higher brightness and porosity of the coatings.