This prospective longitudinal study examined the long-term physical and psychosocial outcomes of adolescents with juvenile-onset fibromyalgia (JFM), compared with healthy control subjects, into early adulthood. Adolescent patients with JFM initially seen at a pediatric rheumatology clinic (n = 94) and age- and gender-matched healthy control subjects (n = 33) completed online measures of demographic characteristics, pain, physical functioning, mood symptoms, and health care utilization at ∼6 years' follow-up (mean age: 21 years). A standard in-person tender-point examination was conducted. Patients with JFM had significantly higher pain (P < .001), poorer physical function (P < .001), greater anxiety (P < .001) and depressive symptoms (P < .001), and more medical visits (P < .001)than control subjects. The majority (>80%) of JFM patients continued to experience fibromyalgia symptoms into early adulthood, and 51.1% of the JFM sample met American College of Rheumatology criteria for adult fibromyalgia at follow-up. Patients with JFM were more likely than control subjects to be married and less likely to obtain a college education. Adolescent patients with JFM have a high likelihood of continued fibromyalgia symptoms into young adulthood. Those who met criteria for fibromyalgia in adulthood exhibited the highest levels of physical and emotional impairment. Emerging differences in educational attainment and marital status were also found in the JFM group. JFM is likely to be a long-term condition for many patients, and this study for the first time describes the wide-ranging impact of JFM on a variety of physical and psychosocial outcomes that seem to diverge from their same-age peers.