Abstract: Addition of a polyether in which one radical is a 2-hydroxyethyl- or 2-hydroxypropyl-terminated chain of two or more oxyethylene or 2-oxypropylene units and the other radical is either a defined hydrocarbon group or the 2-hydroxyethyl group to an aqueous alkaline emulsion in which chloroprene or a mixture of chloroprene with another monomer is undergoing polymerization in the presence of an alkyl mercaptan makes it possible to carry out the polymerization to a high degree of conversion, while at the same time avoiding excessive gel formation. This invention makes possible a significant increase in polymer yield without sacrifice of polymer quality or performance.