A method of inhibiting scale formation in a subterranean formation comprising: (a) injecting a suspension comprising particles of a controlled release scale inhibitor suspended in an aqueous medium into a formation through an injection well wherein the particles have a mean diameter of less than 10 microns, preferably less than 5 microns, more preferably less than 1 micron; (b) allowing the suspension to percolate through the subterranean formation towards a production well; and (c) controllably releasing the scale inhibitor from the particles in the near well bore region of the production well. Suitably, the particles of the controlled release scale inhibitor comprise an esterifiable scale inhibitor cross-linked with a polyol via ester cross-links.