The present invention relates to a process for preparing aqueous active compound compositions of active compounds which are poorly soluble in water, in particular of active compounds for the protection of crops and materials. Moreover, the invention relates to the active compound compositions obtainable by the process and to their use for controlling harmful organisms in plants and in the protection of materials. The process comprises the following steps: a) provision of an aqueous suspension of solid active compound particles of at least one active compound having a solubility in water of not more than 5 g/l at 25° C./1013 mbar, comprising, for stabilizing the active compound particles, at least one surfactant, where the active compound particles in the suspension have a mean particle size, determined by dynamic light scattering, of not more than 1200 nm, b) emulsion polymerization of a first monomer composition M1 in the aqueous suspension of the active compound, where the monomer composition M1 comprises at least 95% by weight, based on its total weight, of at least one neutral, monoethylenically unsaturated monomer M1.1 having a solubility in water of not more than 30 g/l at 25° C./1013 mbar, giving an aqueous dispersion of polymer/active compound particles, and c) emulsion polymerization of a second monomer composition M2 in an aqueous dispersion of the polymer/active compound particles obtained in step b), where the monomer composition M2 comprises at least 60% by weight, based on its total weight, of at least one neutral, monoethylenically unsaturated monomer M2.1 having a solubility in water of not more than 30 g/l at 25° C./1013 mbar.
