This chapter presents an overview, signs and symptoms, diagnosis, treatment, nursing interventions, patient education for the following behavioral and psychosocial conditions: aggressive/disruptive/violent behavior, altered mental status (AMS), anxiety, delirium, dementia, depression, and substance abuse. Violent behavior places patients and caregivers at risk for injury. Agitation and threats of violence should be addressed proactively, and de-escalation of the agitated patient should be prioritized to reduce incidences of violence in the PCU. De-escalating a potentially violent patient can take time but is frequently successful if approached in the correct manner. Complications of AMS include impaired cognitive, behavioral, and physical functioning, which may lead to combative or agitated behavior and place the patient at risk for accidental self-harm (accidental removal of lines, drains, or tubes, falls, etc.). Anxiety in acute illness can result in irrational behavior and impaired cognition, leading to aggression, agitation, and inadvertent removal of important lines, drains, or tubes.