  We argue that theories in which supersymmetry breaking originates at low
energies often contain scalar particles that mediate coherent gravitational
strength forces at distances less than a cm. We estimate the strength and range
of these forces in several cases. Present limits on such forces are inadequate.
However new techniques, such as those based on small cryogenic mechanical
oscillators, may improve the present limits by ten orders of magnitude or
discover new forces as weak as 1 \% of gravity at distances down to 40 microns.
