  We establish Einstein-Hilbert gravity couplings in the effective action for
Intersecting Brane Worlds. The four-dimensional induced Planck mass is
determined by calculating graviton scattering amplitudes at one-loop in the
string perturbation expansion. We derive a general formula linking the induced
Planck mass for N=1 supersymmetric backgrounds directly to the string partition
function. We carry out the computation explicitly for simple examples,
obtaining analytic expressions.
