Аннотация:The sequence of continuum theories of adhesion is discussed. We give a brief analysis of the existing theories of adhesion and present a continuum theory of adhesion as a natural generalization of appropriate options for the theory of elasticity and gradient theories of elasticity. We offer a sequence of variational formulations of theories of adhesion and constitutive equations. In addition, the analysis of the structures of the tensors of adhesive elastic modules is presented. As a result, we propose a classification of theories of adhesion and gradient theories of elasticity in terms accounting for scale effects. The classification is based on the qualitative analysis of scale effects of different orders depending on the physical properties of the continuum.