A mean field approach is used to calculate the freezing temperature Tg in metallic spin glass multilayer systems. We calculate the dependence of Tg( WSG) on the thickness WSG of spin glass layers separated by metallic interlayers of thickness Wil large enough that the spin glass layers are not coupled to one another. We also calculate the dependence of Tg( Wil) on Wil for the case where Wil is small enough to allow coupling between the spin glass layers. Theoretical results are in good agreement with experimental data. Finite-temperature effects, scattering of electrons by nonmagnetic impurities, and intrinsic sd scattering of electrons by the spins play important roles in establishing the trends exhibited by Tg( WSG) and Tg( Wil). A clear physical interpretation is given which explains the behaviours of Tg( WSG) and Tg( Wil) in experimental spin glass multilayers. We also predict how Tg( WSG) and Tg( Wil) will behave if the nonmagnetic impurity concentration is nonnegligible.