  We show how non-trivial form fields can induce an effective potential for the
dilaton and metric moduli in compactifications of type II string theory and
M-theory. For particular configurations, the potential can have a stable
minimum. In cosmological compactifications of type II theories, we demonstrate
that, if the metric moduli become fixed, this mechanism can then lead to the
stabilization of the dilaton vacuum. Furthermore, we show that for certain
cosmological M-theory solutions, non-trivial forms lead to the stabilization of
moduli. We present a number of examples, including cosmological solutions with
two solitonic forms and examples corresponding to the infinite throat of
certain p-branes.
