This paper examines the importance of base flexibility on the nonlinear behaviour of coupled shear walls subjected to pseudo-static lateral loading. The classic continuum method is adopted, with the base flexibility modelled by effective rotational and vertical elastic stiffnesses,KθandKv, respectively. Since the magnitudes of these stiffnesses depend on the properties of the supporting soil and also on the characteristics of the foundation itself, different soils as well as the type of foundation are considered. The latter consists of separate footings under each wall as well as a single combined foundation under the coupled walls. In general, the results show that base flexibility becomes especially important for the overall lateral stiffness at all load levels, whereas internal stresses are affected in only the lower portion of the structure for service loading.Key words: shear walls, coupled, nonlinear, continuum method, flexible bases, separate footings, combined foundation.