The theory of anisotropic elasticity for paper is reviewed. Sonic pulse velocity measurements were used to evaluate Young’s modulus, shear modulus and Poisson’s ratio of paper. The effects of fibre orientation and drying stresses on paper elasticity are readily measured by sonic velocity. A previously proposed relationship between the fourin-plane elastic constants is approximately true for well-bonded paper. Local modulus variations in a single specimen can be detected by sonic velocity measurements. Any dependence of sonic velocity on substance is due to real differences in mechanical properties of the sheet.