Metal‐dielectric nanostructures are synthesized optimizing their capabilities of enhancing Raman scattering and fluorescence emission. Silver nanoparticles with controlled average size and morphology are obtained by dipping porous silicon (p‐Si) specimens in silver nitrate acqueous solutions. The effects of silvered p‐Si in enhancing Raman Scattering were investigated usinga cyanine dye showing detectable concentration as low as 10‐8M.In order to obtain photoluminescence enhancement, silvered p‐Si samples are coated by ultrathin films of amorphous silicon nitride. The analysis of metal‐dielectric nanostructures show an energy red‐shift of the Surface Plasmon resonances connected to the changes of the dielectrics surrounding the metal particles. In particular, the thickness of such a coating can be tuned in order to enhance the fluorescence emission (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)