LAUSR

INTRODUCTION While abundant cross-sectional studies have examined the relationship between stress and problematic internet use (PIU), little is known about the underlying mechanism through which stress influences the development of PIU. To elucidate the mechanism in facilitation of prevention and treatment of PIU, this study tested a moderated mediation model using a longitudinal design in which the impact of stressful life events on PIU was mediated by psychological capital (PsyCap); the dependence of this mediation link on participants' developmental stage was further evaluated. METHODS A total of 1365 middle school and high school adolescents (Mage  = 14.68, SD = 1.56; 47% female) from central China were surveyed over 3 years. RESULTS PsyCap was found to completely mediate the contribution of stressful life events to PIU. In addition, the relationship between stressful life events and PsyCap was moderated by participants' school level, in which the negative impact of stress on PsyCap was stronger in middle schoolers than in high schoolers. CONCLUSIONS These findings support further examination of PsyCap in adolescents' PIU development, with a special focus on developmental changes from middle school to high school.