Objectives: To determine factors that could predict Class II/1 malocclusion patient compliance during functional treatment. Materials and Methods: The sample consisted of 77 subjects (aged 11–13 years ; 47% girls) presenting with Class II/1 malocclusion. Inclusion criteria were distal molar relationship, overjet greater than 5 mm, and confirmed pubertal growth spurt. Removable functional appliances (62% Twin Block [TB], 38% Sander Bite Jumping [BJ]) with built-in maxillary expansion screws were used. Follow-up period was 1 year. Patients and parents independently filled out the Child Perception Questionnaire, Parental/Caregiver Perception Questionnaire, and Family Impact Scale to assess emotional and social well-being, oral symptoms, functional limitations, parental emotions, family activities, conflicts, and financial burden as possible predictors of compliance during treatment. Sex, overjet, and appliance type were also analyzed. Results: There were more noncompliant than compliant patients (55% vs 45%). Parental perception of altered emotional well-being of their children was the strongest predictor, increasing compliance odds 3.4 times (95% confidence interval [CI], 1.2–9.4 ; P = .017). Patients were 3.2 times (95% CI, 1.1– 9.3 ; P = .033) more likely to cooperate with TB compared with BJ appliance. OJ ≥ 8 mm increased compliance odds 3.1 times (95% CI, 1.0–9.4 ; P = .044). Conclusions: Parental perception of child's emotional well-being alteration, severity of malocclusion, and type of appliance are major predictors of compliance. Psychosocial issues and oral function limitations reported by children and family impact are of negligible influence.