Molecular orbital theory has been applied to explore the potential energy surface for several bimolecular reactions. The results of these calculations can be used to assess the rate accelerations that might be achieved in similar optimally oriented reactions. Several of the reactions studied (e.g., CH3O− + H2NCHO) are bimolecular counterparts of intermediate steps in enzyme catalysis (e.g., serine proteinase activity). In these cases the importance of “orbital steering” as a vehicle for enzyme catalysis is assessed.