The goal of this research is to empirically assess the three year immediate effects and 12 year follow-up of the CATCH My Breath (CMB) program on delaying the onset of e-cigarette use with a 6th-9th grade cohort, using a 20-school group randomized controlled trial (RCT), with 1,400 students. E-cigarettes are the most commonly used tobacco product by US youth. Recent research, strongly suggests that youth who only smoke e-cigarettes exhibit symptoms of addiction, and are more likely to experiment combustible tobacco. Unfortunately, few e-cigarette prevention programs exist, and none have been tested for longer-term efficacy. Although some tobacco prevention programs have included an e-cigarette add -on component, to our knowledge, none of these revised programs have been formally evaluated. The lack of e-cigarette specific program content, and lack of rigorous evaluation, warrants the proposed project. CMB was developed with input from school administrators, health education coordinators, tobacco prevention educators, classroom teachers, students, and parents. CMB has been formatively evaluated and pilot tested at 59 middle schools in 7 states, resulting in positive feedback from over 100 middle school teachers and 9,578 6th-8th grade students. Our second pilot pretest-posttest controlled experiment (2017-2018), and resulted in an treatment-control difference of 3.8% in ever smoking over a 16-month period. Given CMB's current popularity with schools as a 'best practice' program, and with initial positive results, a full scale randomized control trial is needed to determine longer term, 6th-9th grade efficacy.