The aim of this study was to investigate growth and treatment changes in patients with Class II Division 1 malocclusion treated with a combined headgear-activator appliance. The sample consisted of 20 consecutive male patients treated with headgear-activator. Their compliance was checked after 2 months of treatment, and 3 patients dropped out. Lateral cephalograms, obtained 6 months before treatment, at the start of treatment, after 6 and 12 months of treatment, and 24 months after treatment, were analyzed by the method of Pancherz. The results disclosed that during growth, on average, overjet, molar relationship, and jaw-base relationship improved, and the mandibular incisors became retruded; the changes were statistically significant over a 2-year period. There was no significant change in the overbite. During the 12 months of treatment, there was no maxillary forward growth, and the jaw relationship improved (P <.001) because of forward growth of the mandible (P <.001). The molar relationship and the overbite improved (P <.001). Significant treatment effects included reduction in overjet (P <.001) and overbite (P <.01), and improvement of jaw-base (P <.05) and molar (P <.001) relationships. There was significant restraint of maxillary forward growth (P <.05). The eruption of the maxillary incisors and molars was restrained (P <.05). The average basic growth pattern in Class II Division 1 malocclusion resulted in small favorable changes in overjet, molar relationship, and jaw-base relationship. The main effect of the headgear-activator appliance was a favorable dental change, limited to restraint of maxillary forward growth but not affecting the vertical dimension.