Why do some people turn to substances after trauma while others move toward connection and meaning? Stress, Trauma and Reward Systems explains how chronic stress reshapes salience, learning, and motivation, tuning the brain toward short-horizon rewards and threat vigilance. We connect mesolimbic dopamine with stress hormones, amygdala–hippocampal memory loops, and prefrontal control to show why urges spike in danger or loneliness—and why avoidance, numbness, and hyperarousal feel briefly “rewarding.” Clinically, this lens clarifies cycles: trauma cues raise arousal; substances dampen distress or amplify energy; negative reinforcement cements habits; shame and withdrawal erase protective routines. We map assessment beyond symptom checklists: ask about context (housing, safety, discrimination), sensory triggers, sleep timing, and social rhythms; screen for PTSD, panic, dissociation, depression, and pain. Treatment integrates exposure-based or cognitive processing work with craving management, contingency supports, and social reconnection. Medication choices are pragmatic: stage SSRIs/SNRIs for core trauma symptoms; use α-adrenergics for nightmares/hyperarousal; pick anti-craving or MOUD options that don’t worsen sleep, weight, or blood pressure; and monitor for stimulant or sedative misuse in patients seeking “nervous system control.” We emphasize habit architecture—anchored wake time, consistent daylight, movement, valued roles—that competes with short-loop reward, plus skills for urge surfing, interoceptive labeling, and cue revaluation. Equity threads run through language access, culturally anchored narratives of healing, and community partnership where safety is fragile. Measurement stays lean: weekly sleep/energy, craving intensity, and “connection minutes.” When teams align biology, context, and skills, Stress, Trauma and Reward Systems, discoverability through a trauma reward conference, and mechanistic anchors like mesolimbic dopamine help transform reflexive coping into durable recovery.