The Neuroscience of Addiction: Brain Function, Neurotransmission, and Clinical Implications is a self-paced professional training designed for behavioral health professionals seeking to better understand addiction from a brain-based and clinically practical perspective. This course introduces participants to the basic structure and function of the brain and nervous system, including how neurons communicate through electrical and chemical signaling. Participants will review key neurotransmitters involved in substance use disorders, including dopamine, serotonin, GABA, glutamate, and endorphins, and examine how psychoactive substances alter normal brain communication. The training explores how addiction develops through changes in reward, motivation, learning, memory, stress regulation, habit formation, and executive functioning. Participants will learn how repeated substance use contributes to tolerance, dependence, withdrawal, cue-induced craving, impaired decision-making, emotional dysregulation, and relapse vulnerability. Special attention is given to the clinical implications of neuroscience-informed care. The course helps clinicians translate complex brain-based concepts into practical assessment, psychoeducation, treatment planning, relapse prevention, and Client engagement strategies. By understanding addiction as a process involving interacting changes in brain systems, clinicians can provide care that is more compassionate, effective, and grounded in current evidence. This course is designed to take approximately 3.5 hours to complete, including review of course materials, applied case reflection, post-test completion, and course evaluation.