Communication: The power of multinuclear solid-state NMR for the investigation of the structural aspects of hybrid organic-inorganic materials is demonstrated by the results presented here. It is shown that information about the organic groups can be obtained from H-1 and C-13 NMR and about the inorganic groups from Al-27 and Si-29 NMR; changes caused by the addition of a hardening component are revealed. Organic-inorganic materials are of interest because they combine properties typical of inorganic compounds with the favorable mechanical properties of synthetic polymers.