This chapter provides a comprehensive overview of memory, exploring how it can become maladaptive in various clinical conditions. It starts by outlining the structural organization of memory, including the modal model, working memory, and the types of long-term memory. The text then details psychophysical and behavioral methods used to quantify memory and maps the key neuromechanisms of memory formation, focusing on brain regions like the hippocampus, the amygdala, and the prefrontal cortex (PFC). The cellular mechanisms of long-term potentiation (LTP) and long-term depression (LTP) are covered. Finally, this chapter examines disorders characterized by memory loss like Alzheimer’s and other forms of dementia, and it discusses other conditions marked by maladaptive memory processes, such as posttraumatic stress disorder (PTSD), dissociative disorders, and addiction.