PURPOSE: To analyze a large national private payer population in the United States for trends over time in hip arthroscopy by age groups and to determine the rate of conversion to total hip arthroplasty (THA) after hip arthroscopy. METHODS: We performed a retrospective analysis using the PearlDiver private insurance patient record database from 2007 through 2011. Hip arthroscopy procedures including newly introduced codes such as osteochondroplasty of cam and pincer lesions and labral repair were queried. Hip arthroscopy incidence and conversion rates to THA were stratified by age. Chi-squared analysis was used for statistical comparison. Conversion to THA was evaluated using Kaplan-Meier analysis. RESULTS: From 2007 through 2011, 20,484,172 orthopaedic patients were analyzed. Hip arthroscopy was performed in 8,227 cases (mean annual incidence, 2.7 cases per 10,000 orthopaedic patients). The incidence of hip arthroscopies increased over 250% from 1.6 cases per 10,000 in 2007 to 4.0 cases per 10,000 in 2011 (P < .0001). Patients in the 40 to 49 age group made up 28% of cases, followed by patients ages 30 to 39 (22%) and 50 to 59 (19%). Patients under 30 years old showed the greatest increase in incidence from 2007 to 2011 (335%), but patients over 60 still had over a 200% increase. Labral debridement was the most common procedure (6,031 cases), and approximately 1.6 procedural codes were billed for every case performed. Labral repair was more common in patients under 30, while labral debridement was more common in older age groups (P = .046). Within 24 months of hip arthroscopy, 17% of patients older than 50 required conversion to THA, compared with <1% of patients under 30 (P < .0001). CONCLUSIONS: Hip arthroscopy procedures are increasing in popularity across all age groups, with patients ages 40 to 49 having the highest incidence in this large cross-sectional population, despite a high rate of early conversion to THA within 2 years in patients over 50. LEVEL OF EVIDENCE: IV, cross-sectional study.