Abstract. We present a variational formulation of combined motion by minus the Laplacian of curvature and mean curvature flow, as well as related flows. The proposed scheme covers both the closed curve case and the case of curves that are connected via triple or quadruple junction points or intersect the external boundary. On introducing a parametric finite element approximation, we prove stability bounds and compare our scheme with existing approaches. The presented scheme has very good properties with respect to the equidistribution of mesh points and, if applicable, area conservation.Key words. surface diffusion, (inverse) mean curvature flow, surface attachment limited kinetics, nonlinear curve evolution, triple junctions, parametric finite elements, Schur complement, tangential movement AMS subject classifications. 65M60, 65M12, 35K55, 53C44 DOI. 10.1137/0606539741. Introduction. The motion of curves or surfaces driven by second or fourth order geometric evolution equations arises in many applications in materials science and, of course, in differential geometry. Well known is the mean curvature flow, where a hypersurface moves in the direction of its mean curvature vector. Also frequently arising are evolution laws where the normal speed of an evolving hypersurface is given as a function of mean curvature, in applications, such as image processing or mathematical physics. In mathematical physics the inverse mean curvature flow plays a role in the context of the positive mass conjecture. In materials science the motion of networks of curves or surfaces is also often important. The evolution of grain networks-arising in polycrystalline materials-is also given by mean curvature flow, where at junctions angle conditions have to hold.Fourth order geometric evolution equations also frequently are found in geometry and materials science. The situation that the normal velocity of a hypersurface is given by minus the Laplacian of mean curvature is called surface diffusion. This evolution law arises in situations where the diffusion of material is restricted to interfacial regions; see, e.g., [36]. When many phases appear, networks also have to be taken into account. As the evolution law is of fourth order, additional conditions, which act as boundary conditions for the evolution law on the curves or surfaces, have to hold.The goal of this paper is to propose and analyze a new approach to numerically solving geometric evolution laws of second and fourth order. The numerical method is variational and very flexible. In particular, it is possible to couple fourth and second order laws on the surfaces or at triple junctions in a straightforward way.