This cephalometric study was designed to evaluate the dentoskeletal anteroposterior and vertical changes produced by Cetlin therapy (lower lip bumper, ACCO, cervical headgear) to correct Class II Division 1 malocclusion in the late mixed dentition. All measurements were made on 2 lateral headfilms, at pretreatment and at 1 year after beginning treatment. The selected sample (n = 110; 67 boys and 43 girls; mean age, 10 to 11 years) and the control group (n = 100; 48 boys, 52 girls; mean age, 10 to 11 years) matched for number, age, and malocclusion. The average observation interval was 13 months. The final measurements between intervals were averaged and tested for significance by analysis of variance. A one-factor (group) repeated measure model and a two-factor (group and facial type) repeated measure model were fitted to each variable separately and significance values were set at P </=.05. The Class I molar relationship was achieved in all treated subjects primarily through distalization of upper first molars. A significant distal tipping was found in 70% of the treated cases. The results showed a significant forward growth limitation of the maxilla with the use of cervical headgear. No significant change of mandibular position was found in the treated group compared with the control group. Both bite opening and proclination of upper and lower front teeth occurred. Cetlin therapy is reliable and effective for space recovery and interceptive Class II Division 1 treatment. Additional therapy may be needed later.