Addiction is under-recognized in later life, where loneliness, pain, insomnia, and polypharmacy reshape risk. Substance Use in Older Adults reframes assessment and care for a population with slower metabolism, more medical comorbidity, and different goals. Presentations are subtle: falls, confusion, memory lapses, depression, or medication “requests” that mask withdrawal, alcohol misuse, benzodiazepine dependence, or escalating opioid exposure. We outline age-attuned screening (AUDIT-C cutoffs, benzodiazepine risk flags, opioid/anticholinergic load), cognitive status checks, and caregiver input—all while respecting autonomy and privacy. Pharmacology demands caution: hepatic/renal changes raise levels; drug–drug interactions abound; and sedative burden drives delirium, apnea, and fractures. We cover safer deprescribing pathways for benzodiazepines and Z-drugs, alcohol pharmacotherapy with careful monitoring, and MOUD choices that consider QTc, constipation, bone health, and fall risk. Psychosocial care centers on grief, role loss, and social isolation: brief MI with dignity-affirming language, problem-solving therapy, and practical activation tied to daytime light, movement, and community meals. Pain and sleep plans must reduce sedatives: non-opioid analgesia, PT, pacing, CBT-I, and caregiver coaching. We discuss residential transitions and hospital-to-home risk: medication reconciliation, naloxone in every discharge where opioids are present, and pharmacist-led reviews. Equity includes fixed incomes, transport, rural distance, and language access; technology needs simplification (big-font instructions, caregiver portals). Measurement focuses on function—falls, sleep efficiency, daytime participation—plus cravings and safety events. With thoughtful pacing and respect for values, Substance Use in Older Adults, program visibility via a geriatric addiction conference, and practical safeguards like polypharmacy management can restore clarity, safety, and connection.