The National Breakthrough Pain Study is a large observational study that assessed breakthrough pain (BTP) in a population of commercially insured community-dwelling patients with opioid-treated chronic pain. Eligible patients were identified from an administrative claims database, and consenting patients were asked to complete a structured telephone interview and several validated questionnaires. Questionnaires assessed pain interference with function (Brief Pain Inventory-Short Form), health status (Short Form 12 [SF-12] Health Survey), disability (Sheehan Disability Scale), work performance (World Health Organization Health and Work Performance Questionnaire), and mood (Generalized Anxiety Disorder-7 Screener [GAD-7] and Patient Health Questionnaire-2 [PHQ-2]). Of 2198 patients interviewed, 1278 patients had persistent pain controlled with opioid therapy; 1023 (80%) of these patients reported BTP. Patients had a median of 2.0 episodes of BTP per day (range, 1-50) and a median duration of BTP of 45 minutes (range, 1-720). Compared with patients without BTP, patients with BTP had more pain-related interference in function (Brief Pain Inventory, mean ± SD: 34.2 ± 15.6 vs 25.0 ± 15.7 [P < 0.001]), worse physical health (SF-12 physical component score: 29.9 ± 9.6 vs 35.1 ± 10.4 [P < 0.001]) and mental health (SF-12 mental component score: 47.4 ± 11.3 vs 49.3 ± 10.4 [P < 0.001]), more disability (Sheehan Disability Scale global impairment score: 15.1 ± 9.1 vs 10.6 ± 8.5; World Health Organization Health and Work Performance Questionnaire absolute absenteeism: 12.4 ± 59.9 vs 7.7 ± 44.9 hours [both P < 0.001]), and worse mood (GAD-7 score: 7.4 ± 5.9 vs 5.9 ± 5.4; PHQ-2 anhedonia score: 1.2 ± 1.1 vs 0.9 ± 1.0 [both P < 0.001]). In this population of community-dwelling patients with opioid-treated chronic pain, BTP was highly prevalent and associated with negative outcomes. This burden of illness suggests the need for specific treatment plans.