 This study investigated the association between psychosocial aspects of mobile phone use and mental health symptoms in a prospective cohort of young adults. The results showed that high frequency of mobile phone use at baseline was a risk factor for mental health outcomes at one year follow-up among the young adults. The risk for reporting mental health symptoms at follow-up was greatest among those who had perceived accessibility via mobile phones to be stressful. This article was authored by Hagberg Matz, Arun Stam Annika, and Tomi Sa.