This thesis estimates the effects of banning mobile phones in 9th grade classrooms on educational results. There is no national policy regarding the use of mobile phones in Sweden, and information regarding mobile phone bans were therefore collected through a survey sent out to all secondary schools in Sweden. The data were thereafter matched with administrative data on educational results provided by the Swedish National Agency for Education. By applying the staggered variation of mobile phone ban implementations across secondary schools in Sweden in a difference-in-difference design, I find positive and significant results on both the final grade point scores and the share of pupils that pass with approved score in all subjects.