  We introduce the concept of Random Multi-Overlap Structures in diluted spin
glasses, following the ideas of Aizenman, Sims and Starr for non-diluted
models. As a result, we prove the generalized bound and variational principle
for the free energy per site, in analogy with the results of Aizenman, Sims and
Starr for non-diluted models. We also prove some stability properties of the
optimal RMOSt, analogous to the one found by Guerra for non-diluted models.
