Objectives: To compare the skeletal, dentoalveolar and soft tissue effects of the AdvanSyncTM appliance with intermaxillary elastics in the correction of Class II malocclusions in growing patients. Materials and Methods: A retrospective study was conducted using lateral cephalograms of patients taken pre-treatment (T1) and post-comprehensive orthodontic treatment (T2). 41 patients consecutively treated with AdvanSyncTM were compared to 41 similar patients treated with intermaxillary Class II elastics. All patients had significant growth potential during treatment, as assessed by cervical vertebral maturation. A comparison group was generated from historical databases and matched to the experimental groups for skeletal age, gender and craniofacial morphology. Treatment changes were evaluated between the time points using a custom cephalometric analysis generating 31 variables as well as regional superimpositions. Data was analyzed using one-way analysis of variance and Tukey-Kramer tests. Results: The effects of AdvanSyncTM and fixed orthodontics (T2-T1) included maxillary growth restriction, protrusion, proclination and intrusion of mandibular incisors as well as mesialization of mandibular molars (p<0.01). The effects of Class II elastics and fixed orthodontics were similar to AdvanSyncTM, with the exceptions of less maxillary growth restriction and greater retrusion and retroclination of maxillary incisors (p<0.01). Significant mandibular growth stimulation, relative to untreated controls, did not occur with either modality. Conclusion: AdvanSyncTM and intermaxillary elastics were effective in normalizing Class II malocclusions during comprehensive fixed orthodontics. AdvanSyncTM produced its effects through maxillary skeletal growth restriction and mandibular dentoalveolar changes. Class II elastics worked primarily through dentoalveolar changes in both the maxilla and mandible.