Recently, studies have demonstrated that two types of Class II subdivision malocclusions can be distinguished and a systematic approach has been developed to diagnose and assist handling of asymmetric malocclusions with specific treatment protocols. This lecture will describe this systematic approach and the rationale for selection of the most appropriate treatment protocol to be used in each of these subdivision types, based on their characteristics. Analogously, the same rationale for treatment of Class III subdivision malocclusions will be shown. Investigations supporting the treatment rationales will also be provided.