The #Tamojunto2.0 program (Unplugged) has been evaluated in Brazil in order to support its implementation as a national public policy. The aim of this study was to evaluate the implementation process of the #Tamojunto2.0 school-based program, disseminated by the Ministry of Health, in the prevention of alcohol and other drug use among adolescents. This is a mixed-methods study. The sample consisted of 13 teachers and eight managers of 8th grade classes of elementary education public schools located in two cities, and a training provider professional for the program’s application. Observation, evaluation and semi-structured interview forms were used. Descriptive and thematic analyses were performed. The results indicate low implementation fidelity, good quality in the application of the program, and high student absenteeism. Aspects which facilitate or hinder implementation of the program are also presented. Such results are relevant for the large-scale implementation of #Tamojunto2.0.