 The nature of the covalent bond has been the subject of considerable discussion in the recent philosophy of chemistry literature (Berson 2008; Hendry 2008; Weisberg 2008). While the chemical bond plays a central role in chemical predictions, interventions, and explanations, it is a difficult concept to define precisely. Fundamental disagreements exist between classical and quantum mechanical conceptions of the chemical bond, and even between different quantum mechanical models. Once one moves beyond introductory textbooks to advanced treatments, one finds many theoretical approaches to bonding, but few if any definitions or direct characterizations of the bond itself. While some might attribute this lack of definitional clarity to common background knowledge shared among all chemists, we believe this reflects uncertainty or maybe even ambivalence about the status of the chemical bond itself.