We discuss the role of several additives used with ceria-based dispersions to polish silicon dioxide films and investigate their interaction with both the abrasives and silicon dioxide films using several techniques. Our results suggest that the amount of adsorption of the additives on the ceria abrasives controls the reactivity of the abrasives with the silicon dioxide film and, hence, the silicon dioxide removal rates (RRs). With several additives, the complete blockage of the reactive species and the reduction of the oxide RR to <2 nm/min occur only when the amount of the additive adsorbed has reached a limiting value. (C) 2010 The Electrochemical Society. [DOI:10.1149/1.3457387] All rights reserved.