The present invention relates to aqueous dispersions comprising a nanoparticulate formulation of crop protection agents in which the nanoparticles have core-shell structures having a mean particle diameter of 0.05 to 2.0 .mu.m and the crop protection agent is present in the core X-ray amorphous together with one or more polymers and the shell consists of a stabilizing coating matrix,preparable by a process which comprises (a) preparing a solution of the crop protection agent in a water-miscible organic solvent, (b) mixing the solution obtained in step (a) with the core polymer or a solution of the core polymer in a water-miscible organic solvent, where the polymer is not or only partially soluble in water or aqueous solutions or water/solvent mixtures, and (c) bringing the mixture resulting from (b) into contact with an aqueous solution comprising components of the coating matrix.