Officially Contract law ignores fault. However, an unofficial story complements the official one, and explains why fault occasionally slips into contract law through doctrines such as willful breach. This chapter of FAULT IN AMERICAN CONTRACT LAW (Omri Ben-Shahar & Ariel Porot, eds, Cambridge U. Press, forthcoming 2010) argues that the official and unofficial stories operate in productive tension to both facilitate ex ante planning and, when necessary, look backward at reasons for breach to reach a just result. The occasional presence of fault in contract law, in this view, represents merely one more instance of the common doctrinal pattern of general rules tempered by exceptions.