Slurries used in the manufacturing of microelectronic devices, and apparatuses and methods for making and using such slurries. In one aspect of the invention, a planarizing slurry for planarizing a microelectronic-device substrate assembly is made by fracturing agglomerations of abrasive particles in a first slurry component into smaller agglomerations of abrasive particles or individual abrasive particles. The first slurry component can include water and the abrasive particles. The agglomerations of abrasive particles can be fractured into smaller units by imparting energy to the first slurry component before the first slurry component is mixed with a second slurry component. The agglomerations of abrasive particles are preferably fractured by imparting sonic energy to the first slurry component before it is mixed with the second slurry component. The agglomerations of abrasive particles in the first slurry component may also be fractured by ball milling or highly turbulent pumping. After fracturing the agglomerations of abrasive particles into smaller units, the first slurry component is mixed with the second slurry component. Another aspect of the invention is inhibiting re-agglomeration of the abrasive particles after mixing the first and second slurry components.