A review covering structure and preparation of thermoset-layered (intercalated, exfoliated) silicate (mainly montmorillonite (M-x[Al4-xMgx](Si-8)O-20(OH)(4) M = exchangeable bases) nanocomposites, X-ray structural studies (small-angle X-ray scattering, transmission electron microscopy), methods of preparation, and physical properties of montmorillonite(6 vol%)-PP and montmorillonite (2 or 5.5 vol%)-PA6 compared with those of talc(25 vol%)-PA nanocomposites.