Definition of the trajectory followed by a nucleophile in its addition to a Pi-system with an adjacent chiral center has immediate application (1) toward organic synthetic strategies aimed at achieving maximum asymmetric induction, and (2) in the understanding of the high stereospecificity accompanying the conversion of prochiral centers to chiral centers in enzymatic reactions. A simple theoretical model, now in initial development, will be expanded to account for the attractive electronic terms controlling stereochemistry. An experimental program is proposed to verify the predictions of this model. The acyclic stereoselection exhibited by carbon-carbon bond forming reactions, such as additions to carbonyl groups, aldol condensations, and conjugate additions to Alpha, Beta-unsaturated systems, will be studied.