BACKGROUND Juvenile-onset recurrent respiratory papillomatosis (JORRP) is an infrequent but debilitating disease. Because JORRP is uncommon, it has proven difficult for studies at single institutions to accurately evaluate its natural history. OBJECTIVE To characterize the clinical spectrum of JORRP. METHODS Standardized retrospective and prospective medical record abstraction. METHODS Twenty-two tertiary-care pediatric otolaryngology centers throughout the United States. Patients All patients with JORRP younger than 18 years seen between January 1, 1996, and March 31, 2002. METHODS Demographics, age at diagnosis, anatomic sites of disease, longitudinal disease course, frequency of surgery, need for tracheotomy, and medication history. RESULTS The registry includes 603 children. The mean age at diagnosis was 4.0 years. The children underwent a mean of 5.1 surgeries annually. Current age, rather than age at diagnosis, was the primary determinant of surgical frequency. The larynx was involved at the time of diagnosis in 96.1% of children, and 87.4% had only 1 anatomic site involved. Children with 1 site involved were significantly older at diagnosis (mean age, 3.9 years) than those with 2 sites (mean age, 2.9 years). Most (74.2%) had stable disease over time, 5.8% showed progression of papillomas to new sites, and 17.9% had no evidence of disease for at least 1 year. Children with disease progression were diagnosed at a significantly younger age than those who remained stable or became disease-free. Children who required tracheotomy were significantly more likely to have progressive disease. CONCLUSIONS The registry has established the clinical course of JORRP in a large sample representative of the United States. Young age was the most important determinant of disease severity (frequency of surgery, extent of disease at diagnosis, and progression of disease). Addressing questions of pathogenesis and disease course will require a revised data collection instrument and molecular analysis of tissues.