Abstract: The present invention relates to microspheres comprising hyaluronan derivatized with a bifunctional crosslinker to form microspheres. Methods of making such microspheres, comprising mixing hyaluronic acid and a dihydrazide with a crosslinker in an aqueous solution, adding a solvent and an emulsifying agent to form an emulsion, and lowering the pH of the emulsion to allow intramolecular and intermolecular crosslinking to occur, are also disclosed. The invention also provides for pharmaceutical or cosmetic formulations based on the microspheres described herein, further containing one or more active or cosmetic agents, and methods of using such formulations.