How are these memories formed and stored? Can they be changed? I will discuss studies from my laboratory showing that memory consolidation and storage, the processes that underlie long-term memory, are very dynamic and critically involve mechanisms regulated by the stress hormones glucocorticoids. I will discuss data showing how the process of memory reconsolidation – a post-retrieval restabilization of a labile trace – opens a window of opportunity for strengthening or weakening memories as well as creating new memory traces through new processes of consolidation. In animal models, we have identified mechanisms that can strengthen memories and prevent forgetting by tapping into the consolidation and reconsolidation processes. We have also identified treatments that disrupt memory reconsolidation and may serve as potential therapeutic approaches for weakening traumatic memories or memories induced by drugs of abuse. I will show data supporting the conclusion that the main function of reconsolidation is to contribute to the lingering consolidation process and mediate memory strengthening. Finally, I will discuss the literature and our results regarding the influence of the passage of time on the reconsolidation of memory. These points have important implications for the use of memory consolidation and reconsolidation in therapeutic settings.