A process for preparing a composition by free-radical polymerization of a monomer composition comprising: a) at least one ethylenically unsaturated carboxylic acid containing monomer or anhydride thereof; b) optionally at least one ethylenically unsaturated monomer different from a) but copolymerizable therewith; and c) at least one crosslinking monomer containing at least two ethylenically unsaturated groups. The monomer composition is polymerized in an organic medium having a solubilizing effect on one or more of the monomeric ingredients, but substantially none on the resulting polymer. The polymerization is conducted in the presence of a free radical forming catalyst and at least one steric stabilizing polymer polymerized from a vinyl lactam and a copolymerizable monomer selected from a short chain alkyl ester of (meth)acrylic acid, a long chain alkyl ester of (meth)acrylic acid, and combinations thereof.