Tobacco use is of high prevalence among Spanish adolescents. Programming to counteract tobacco use has been needed. There is a lack of knowledge on the efficacy of teen tobacco use cessation programming. The current study provides an immediate outcome evaluation of the Project EX tobacco use prevention and cessation program among Spanish adolescents. An eight-session, classroom-based curriculum was translated from English to Spanish and adapted to the Spanish culture. Next, it was tested using a randomized controlled trial with 1,546 Spanish students, involving three program and three control high schools. Participants at the program group provided moderately favorable process ratings of the program. Compared to the standard care control condition, the program condition revealed a greater reduction in smoking intentions and CO ppm levels.