In supersymmetric models, the well-known tension between naturalness and experimental constraints is relieved if the squarks and sleptons of the first two generations are superheavy, with masses m(heavy) ≥ 10TeV, and all other superpartners are light, with masses m(light) ≤ 1 TeV. We show that even if all scalar masses and trilinear A parameters are of order m(heavy) at some high scale, a hierarchy of m(heavy)/(2)m(light)/(2) ~ 400 may be generated dynamically through renormalization group evolution. The required high energy relations are consistent with grand unification, or, alternatively, may be realized in moduli-dominated supersymmetry-breaking scenarios. (C) 2000 Published by Elsevier Science B.V.