An amphiphilic proline-based organocatalyst was assembled on the interface of water and oil, resulting in a W/O emulsion. The chiral catalyst in emulsion significantly enhances the reactivity and stereoselectivity of the direct asymmetric aldol reactions, which can be attributed mainly to the larger interfacial surface area and uniformly distributed catalyst molecules in the interface of the emulsion droplets. (c) 2007 Elsevier Inc. All rights reserved.