We consider a model of a two-dimensional interface of the (continuous) SOS type, with finite-range, strictly convex interactions. We prove that, under an arbitrarily weak pinning potential, the interface is localized. We consider the cases of both square well and delta potentials. Our results extend and generalize previous results for the case of nearest neighbours Gaussian interactions in [7] and [1]. We also obtain the tail behaviour of the height distribution, which is not Gaussian.