The controllability of systems described by population balance equations through the use of lumped manipulated variables is addressed. A comprehensive model is first presented and then simplified in order to make some general results possible. More detailed analysis is undertaken for several specific systems : human population dynamics, emulsion polymerization, and crystallization. These encouraging controllability results for particulate processes suggest that the application of appropriate control stategies for the control of the particle size distribution through the manipulation of feed concentrations could be successful in practical situations.