We have prepared pure alumina and silica-doped alumina (9:1 Al:Si atom ratio) aerogels by supercritical drying of monolithic alcogels formed by slow, sub-stoichiometric (H2O:Al=2.2) hydrolysis of solutions of alkoxide precursors (aluminum s-butoxide and tetraethyl orthosilicate) in s-butanol. Both aerogels were X-ray indifferent over a large temperature range, first ordering as the eta transition form upon calcination at 1173 K. The silica dopant retarded sintering of the aerogel, thereby enhancing its surface area and delaying crystallization of alpha-alumina from 1373-1473 K. Silica did not, however, affect the surface-chemical properties of the X-ray amorphous alumina, both aerogels were inert to pyridine adsorption and butene isomerization probes at 523 K. Stabilization of structure and texture without alteration of surface-chemical properties is a result of the high dispersion of the silica dopant throughout the aerogel＇s bulk. Incorporation of silicon atoms into the growing pre-alumina network facilitates their insertion into vacancies in the transition alumina structure, thereby restricting lattice diffusion as a route for crystallization of the alpha phase.