Research on the reconsolidation effect was greatly revitalized by the highly analytic demonstration of memory reconsolidation (Nader et al. Nature 406:722-726, 2000) in a well-defined behavioral protocol (auditory fear conditioning in the rat). Since this study, reconsolidation has been demonstrated in hundreds of studies over a range of species, tasks, and amnesic agents. Evidence for reconsolidation does not come solely from the behavioral level of analysis. Cellular and molecular correlates of reconsolidation have also been found. In this chapter, I will first define the evidence on which reconsolidation is concluded to exist. I will then discuss some of the conceptual issues facing the field in determining when reconsolidation does and does not occur. Lastly I will explain the clinical implications of this effect.