Background: The present study investigated associations in gender dyads of parents’ and adolescents’ time spent on television and video viewing (TV/DVD), and computer and electronic game use (PC/games) at the ages of 11 and 13 years. Possible mediating effects of parental modelling and parental regulation in the relationship between parental education and adolescents’ prospective TV/DVD and PC/game time were further examined. Methods: A total of 908 adolescents, participating at both ages 11 and 13 years in the Norwegian HEalth In Adolescents (HEIA) cohort study (2007–2009), were included in the analyses. Data on adolescents’, mothers’ and fathers’ self reported time spent on TV/DVD and PC/games were measured at both time points by questionnaires. Correlation coefficients were used to examine gender dyads of parents’ and adolescents’ reports. Mediation analyses using linear regression investigated possible mediation effects of parental modelling and parental regulation in the prospective relationship between parental education and adolescents’ time spent on TV/DVD and PC/games between the ages of 11 and 13 years. Results: Correlations of screen time behaviours in gender dyads of parents and adolescents showed significant associations in time spent on TV/DVD at the age of 11 and 13 years. Associations between mothers and sons and between fathers and daughters were also observed in time spent on PC/games at the age of 11 years. Maternal and paternal modelling was further found to mediate the relationship between parental education and adolescents’ prospective TV/DVD time between the ages of 11 and 13 years. No mediation effect was observed for parental regulation, however a decrease in both maternal and paternal regulation at the age of 11 years significantly predicted more TV/DVD time among adolescents at the age of 13 years. Conclusion: Cross-sectional and longitudinal relationships were observed in gender dyads of parents’ and adolescents’ screen time behaviours at the ages of 11 and 13 years, and further studies including both parents and their children should be emphasized. Moreover, maternal and paternal modelling were found to be important target variables in interventions aiming to reduce social differences by parental education in adolescents’ prospective time spent on TV/DVD.