The process evaluation found that 195 teachers from 9 European countries participated in the training, which included information on the theoretical background of the program, drug properties and drug-related problems, the teacher's role in group dynamics, and administrative issues. Regarding implementation of the basic curriculum, approximately half of the classes in the sample conducted all of the curriculum units. On average, each curriculum unit was taught to 78 percent of the enrolled students. There was a high adherence to the implementation of parents' workshops; however, parents' attendance was low. The themes and objectives of the basic intervention units were outlined during three international meetings. A number of criteria guided the design of the core program. The program objective was primary substance abuse prevention (tobacco, alcohol, and other drug use) for students ages 12-14. The basic program was designed for teachers to deliver it within the regular school schedule. The curriculum consists of 12 units, each designed to be implemented within 1 or 2 lessons. The information addresses a broad range of substances, including tobacco, alcohol, and illicit drugs, particularly cannabis. A peer-led intervention complements the basic curriculum. Selected students act as supporters and supervisors of the classroom activities. The curriculum also has a family component, which can complement the basic curriculum by providing students' parents with educational tools that support the school curriculum. Teacher training is a critical element of the program, as it ensures a uniform, and high-quality implementation of the program. 4 tables, 2 figures, and 22 references