In this paper, a continuum membrane theory and its subsequent finite element approximation for the description of arbitrary shell-like nanostructures such as graphene-based nanostructures is presented. This is carried out by applying a multiscale approach where the continuum membrane is linked to the underlying atomistic lattice. This linkage is performed by the exponential generalization of the Cauchy-Born hypothesis, because the classical Cauchy-Born hypothesis is restricted to three-dimensional bulk structures and is thus not applicable to shell-like structures. However, the approximations of the exponential Cauchy-Born hypothesis published so far are limited to structures with a planar reference configuration. In this paper, we present an extended approximation, which does not require the reference configuration to be planar and is thus applicable to arbitrarily shaped shell-like nanostructures. A detailed elaboration of the related finite element implementation with important computational aspects is presented. Finally, the accuracy of the proposed method and its implementation is verified with several numerical examples.A GENERAL APPROXIMATION OF THE EXPONENTIAL CAUCHY-BORN HYPOTHESIS 749 introduced by Arroyo and Belytschko and applying the exponential Cauchy-Born hypothesis, but in contrast to the implementations presented in the literature (applying the simplification for planar reference configurations) [14,17], an approximation of the inverse exponential map is used as well. By doing this, the new method is no longer restricted to planar reference configurations, and the aforementioned initial transformation step is no longer required. The new finite membrane element developed in this work accounts for both the material nonlinearities (in terms of a nonlinear constitutive equation) and the geometrical nonlinearities (in terms of a geometrically exact formulation). The main idea of this work has already been presented by the current authors in [18]. Now, we present a detailed derivation of the method and a thorough analysis of its capabilities.The paper is organized as follows. In the beginning (Section 2), the essential basics of continuum mechanics and differential geometry are reviewed in view of a clear definition of the used terms and concepts. The basic idea of homogenization of atomistic structures in terms of the standard Cauchy-Born hypothesis for space-filling crystals is introduced in Section 3 and its limitation for the application to shell-like nanostructures is discussed subsequently. The different extensions of the classical Cauchy-Born hypothesis for the analysis of shell-like nanostructures, namely, the higher-order Cauchy-Born hypothesis introduced by Sunyk and Steinmann [19] and the exponential Cauchy-Born hypothesis introduced by Arroyo and Belytschko [14], are discussed. Section 4 investigates the approximation of the exponential Cauchy-Born hypothesis. The simplified approximation of the exponential Cauchy-Born hypothesis introduced by Arroyo and Belytschko [15] is summarized, and, ...