Rare-earth silylamides [Ln{N(SiMe3)(2)}(3)] [1a-d, Ln = Y (1a), La (1b), Nd (1c), Sm (1d)] react with partially dehydroxylated silica to generate the singly surface-bonded species [(SiO)Ln{N(SiMe3)(2)}(2)] (2a-d). Trimethylsilylation of silanols occurs during the grafting process, affording in fine a hydroxyl-free surface. Contacting these well-defined surface species with excess triphenylphosphine oxide yields [(SiO)Ln{N(SiMe3)(2)}(2)(OPPh3)] surface adducts 3a-d as the major (80%) species, leaving about 20% of unreacted siloxide bisamido species (20%). In addition to elemental analysis and infrared spectroscopy, solid-state NMR spectroscopy was used to characterize these new materials and proved to be a particularly efficient tool for the study of the paramagnetic Nd- and Sm-containing materials and for providing unambiguous verification of OPPh3 coordination on the rare-earth center. Silica-supported rare-earth amides 2a-d are active catalysts for 1-hexene and styrene hydrosilylation and for phenylacetylene dimerization. When compared to the molecular species 1a-d, grafting of the catalyst induces significant changes in the activity and selectivity of these systems.