  We show that the R\'enyi entropies of single particle, extended wave
functions for disordered systems contain information about the multifractal
spectrum. It is shown for moments of the R\'enyi entropy, $S_{n}$, where
$|n|<1$, it is possible to extract universal information about the
multifractility of such systems. This is shown through a generic calculation
and then illustrated through two example models. We find good agreement between
our analytic formula and numerical simulations of the two test models. Our
formalism is easily extendable to generic non-interacting fermion models. It is
also suggested that recent experimental advances in measuring the multifractal
spectrum might allow some moments of the R\'enyi entropy to be measured.
