Desktop software utilizing physical property prediction algorithms has been developed to allow the prediction of LogP, pKa and LogD values directly from molecular structures. Using batch mode prediction capability to generate these values it is now possible to populate combinatorial libraries with predicted values and utilize these parameters as constraints for the screening of these libraries according to physical property characteristics. One recent development is the ability to perform LogP predictions following generation of a User Database containing molecular structures and measured LogP values unique to a particular laboratory and therefore to a specific set of molecules.