Crystallization or precipitation of cyclodextrins in the presence of racemates has proven to be a useful method to enrich enantiomers. The technique is commonly performed in neat aqueous solutions which limits its utility in resolving many hydrophobic compounds with poor water solubility. In this work we demonstrate that it is possible to enhance the enantiomeric enrichment of (±)-3- imethylaminopropiophenone using organic cosolvents via β-cyclodextrin precipitation. In addition, an equation that allows the calculation of the production efficiency of an enantiomeric enrichment is proposed and utilized. Water plus various organic solvents, including methanol, ethanol, isopropanol, I-propanol, tert-butanol, and acetonitrile, are studied as cosolvents. Several factors are investigated in terms of their effect on the enantiomeric enrichment including a) molar ratio of β-cyclodextrin to analyte, b) solubility of the analyte, c) solubility of β-cyclodextrin, d) solution pH, and e) amount of analyte coprecipitated with P-cyclodextrin. The production eficiency of enantioselective crystallization in cosolvents is evaluated. The use of appropriate organic cosolvents appear to increase the usefulness of cyclodextrin coprecipitations for the production of enantiomerically enriched compounds. © 1995 by Marcel Dekker, Inc.