Background: Multimodal therapy is the standard treatment for pediatric rhabdomyosarcoma, but for adolescents and young adults (AYAs: ages 15–39) and older adults with rhabdomyosarcoma, the use of adjuvant therapy is variable, and survival is greatly decreased compared with younger patients. Methods: All patients with rhabdomyosarcoma who had a curative operative were identified from the 1998–2012 National Cancer Database. Regression analyses identified independent factors relating to receipt of multimodal therapy (resection + chemotherapy + radiation) and the influence of multimodal therapy on 5-year overall survival. Results: Of 2,312 patients, 44% were pediatric (age < 15 years), 22% AYA (ages 15–39), and 34% adult (age ≥ 40 years). Adults received multimodal therapy least often (pediatric: 62%, AYA: 46%, adults: 24%; P <.001), even after controlling for demographic characteristics, tumor features, and stage. In the entire cohort, multimodal therapy was associated with a decreased risk of death within 5 years (hazard ratio [HR] 0.72, 95% confidence interval [CI] 0.62–0.84), with similar findings after stratification by age (pediatric: HR 0.64, 95% CI 0.48–0.85; AYA: HR 0.72, 95% CI 0.55–0.95; adult: HR 0.74, 95% CI 0.58–0.93). In AYAs only, black and Hispanic patients had an increased risk of death within 5 years (black patients: HR 1.64, 95% CI 1.14–2.37; Hispanic patients: HR 1.62, 95% CI 1.11–2.36). Conclusion: This first large national study suggests that multimodal therapy is independently associated with improved survival for both AYAs and adults with rhabdomyosarcoma, similar to pediatric patients, but multimodal therapy is appreciably underused. Implementation of multimodal therapy for all patients could potentially improve overall outcomes of patients with rhabdomyosarcoma.