Background and aims: Parental depressive symptoms may aggravate the effects of children?s emotional problems on risks for Internet gaming disorder (IGD). Here we examined the joint effects of children?s emotional problems and parents? depressive symptoms on the incidence of IGD. Methods: A large prospective, population-based cohort tested potential interactions between children?s emotional problems, parents? depressive symptoms, and incidence of high risk of IGD (HRIGD). Family dyads (n52,031) that included children who were non-HRIGD at baseline completed assessments of childhood and parental affective symptomatology. HRIGD was assessed at baseline and 12 months. Relative excess risk due to interaction (RERI) estimated the magnitudes of interactions. Results: In terms of risk for the development of IGD, parental depression was 1.8 times greater, children?s emotional problems were 2.9 times greater, and both risk factors together were 6.1 times greater than the background risk, with the last two findings reaching statistical significance. The expected risk for the development of HRIGD was RR53.7. Discussion and conclusions: Children?s emotional problems demonstrated a particularly strong relationship with HRIGD. Joint effects of children?s emotional problems and depressive symptoms in parents on the incidence of HRIGD were stronger than the sum of the independent effects of each factor. The findings suggest that combining interventions for the treatment of children?s emotional problems and parents? depressive symptoms may have extra risk reduction effects on preventing IGD in children and adolescents.  Kulcsszavak: internet gaming disorder, emotional problem, depressive symptoms, joint effect, longitudinal, adolescents