Background: Training middle school students to perform hands-only cardiopulmonary resuscitation (HOCPR) is a potential method to increase overall rates of bystander cardiopulmonary resuscitation (CPR). We aimed to examine the feasibility of teaching this population CPR using teacher-implemented education sessions guided by American Heart Association (AHA) training kits and resources. Methods: We conducted a national HOCPR training campaign in middle schools during the 2014-2015 school year. Participating schools utilized AHA CPR training kits to train seventh and eighth grade students. We assessed pretest/posttest knowledge and comfort in performing HOCPR. Results: We recruited 1131 schools and trained approximately 334,610 students in HOCPR. The average pretest score on knowledge questions was 50% and the average posttest score was 84%. Most students (76%) felt comfortable performing HOCPR after the education session. Overall, 98% of teachers said they would continue to implement CPR training in the future. Conclusions: Large-scale, teacher-implemented CPR education sessions in the middle school setting are a successful approach to increase middle school student's knowledge and comfort in performing HOCPR and to increase overall bystander CPR rates.