  We consider the Casimir effect between two parallel plates localized on a
brane. In order to properly compute the contribution to the Casimir energy due
to any higher dimensional field, it is necessary to take into account the
localization properties of the KK modes. When no massless mode appears in the
spectrum, the correction to the Casimir energy is exponentially suppressed.
When a massless mode is present in the spectrum, the correction to the Casimir
energy can be, in principle, sizeable. Here we illustrate a new method to
compute the correction to the Casimir energy between two parallel plates,
localized on a brane. The Casimir energy is suppressed by two factors: at
lowest order in $\varepsilon$, the correction comes entirely from the massive
mode and turns out to be exponentially suppressed; the next-to-leading order
correction in $\varepsilon$ follows, instead, a power-law suppression due to
the small wave function overlap of the zero-mode with matter confined on the
visible brane. Generic comments on the constraints on new physics that may
arise from Casimir force experiments are also made.
