Cross-sectional studies have shown that both stressors and personality vulnerability are risk factors for adolescent problematic Internet use (PIU). However, little is known about how both categories of factors in combination may contribute to the longitudinal development of PIU among adolescents. The aims of this study were to document the developmental pattern of PIU among adolescents and to examine how stressful life events and the Big Five personality traits jointly affect the development of PIU. We tested three competing models: the additive, diathesis-stress, and social push models. A to...