  We study $D$-dimensional polymerized membranes embedded in $d$ dimensions
using a self-consistent screening approximation. It is exact for large $d$ to
order $1/d$, for any $d$ to order $\epsilon=4-D$ and for $d=D$. For flat
physical membranes ($D=2,d=3$) it predicts a roughness exponent $\zeta=0.590$.
For phantom membranes at the crumpling transition the size exponent is
$\nu=0.732$. It yields identical lower critical dimension for the flat phase
and crumpling transition $D_{lc}(d)={2 d \over {d+1}}$ ($D_{lc}={\sqrt{2}}$ for
codimension 1). For physical membranes with ${\it random}$ quenched curvature
$\zeta=0.775$ in the new $T=0$ flat phase in good agreement with simulations.
