Polyamidoamine dendrimers up to the fourth generation have been grown with unprecedentedly high loading within the channels of pore-expanded (10.6 nm) MCM-41 silica. In-depth characterization using nitrogen adsorption, solid-state NMR, FTIR, thermogravimetry, and elemental analysis showed that the dendrimers grow inside the channels with an average yield better than 99 %. The pore size and structure of the support have been found to be determining factors as to how much dendrimer growth can be achieved.