Aim: To focus on the efficacy of the Herbst appliance in the treatment of Class II malocclusions that otherwise would have been difficult without tooth extractions or orthognathic surgery measures. Methods: Evidence-based study and review of our recent clinical, cephalometric roentgenographic, and magnetic resonance imaging research. This research reveals that growth modification with the Herbst appliance is successful in older Class II patients, who are generally considered unresponsive to therapy with removable functional appliances. Conclusions: We suggest a change in the current concept of Class II treatment, with growth adaptation through use of the Herbst appliance in children, adolescents, postadolescents, and young adults. World J Orthod 2000;1:17–31.