Background: In France, uptake of the recommended human papillomavirus (HPV) vaccination remains low. The vaccine cannot be administered without parental consent, but studies have shown that adolescents can make informed decisions about their health. We aimed at understanding the weight of adolescents' vaccination intention in parents' vaccination decision, using data from parent-adolescent dyads collected at baseline of a randomized trial of vaccine promotion interventions. Method: About 649 parent-adolescent dyads from 61 middle schools in France independently completed an online questionnaire on their knowledge and attitudes toward HPV vaccination, structured around the seven psychological domains of vaccine readiness (VR). We used multivariate and path analyses to understand the family decision-making process. Results: HPV vaccination was reported by 50.1% of adolescents and 45.5% of parents. Individual antecedents of VR were poorly correlated within dyads (r = .14-.36). Vaccine intentionality among parents of girls depended both on their own VR (β = .53, p < .001) and on their daughters' vaccine intention (β = .25, p < .001). But among parents of boys, vaccine intention depended only on their own VR (β = .72, p < .001). Adolescents' VR depended more strongly on the social environment's attitude among boys than among girls (β = .54 vs. .34, p < .01). Conclusions: The defined model showed shared decision processes between parents and adolescent girls, but not boys, which can be understood in the context of a recent expansion of HPV vaccination to boys. Beyond this, it suggests that promotion targeting adolescents and their social environment can have a positive influence on parental intentions. (PsycInfo Database Record (c) 2024 APA, all rights reserved). Trial registration: ClinicalTrials.gov NCT04945655.