  The force experienced by objects embedded in a correlated medium undergoing
thermal fluctuations--the so-called fluctuation--induced force--is actually
itself a fluctuating quantity. We compute the corresponding probability
distribution and show that it is a Gaussian centered on the well-known Casimir
force, with a non-universal standard deviation that can be typically as large
as the mean force itself. The relevance of these results to the experimental
measurement of fluctuation-induced forces is discussed, as well as the
influence of the finite temporal resolution of the measuring apparatus.
