It has been known for some time that compactifications of M-theory on manifolds of G_2 holonomy lead to four dimensional low energy theories with N=1 supersymmetry, but only in the last few years has their phenomenology been studied extensively. In this talk I will present the calculation for the Kahler potential on a class of G_2 manifolds constructed by Joyce and show how, in combination with a superpotential from flux and membrane instantons, this can lead to moduli stabilization.