The article reports central findings from the evaluation of the State of Baden-Württemberg program towards prevention and health promotion in schools. The employment of a theory-based evaluation model enabled the interrelation of the summative assessment of program success with the formative evaluation of implementation quality of the program and its optimization. In order to carry out the pre-post comparison, about 2000 students, 1.700 parents and 235 teachers were surveyed at three measurement time points and also individual interviews as well as focus group interviews were employed in a qualitative-quantitative methodological concept. Findings show, that preventative measures in the sense of the theory-based evaluation model result in an improvement of the classroom atmosphere and of the sense of belonging to school among students, accompanied by a reduction of violence. The theory-based evaluation model allowed for more detailed analyses of the implementation effi ciency and for the deduction of suggestions for optimization that could be easily implemented in the fi eld. The theory-based evaluation model is discussed in terms of its use both as part of the evaluation methodology itself and, furthermore, as a product of the evaluation, which emerges and is further differentiated in the process of evaluation.

Keywords
Theory-Based Evaluation Model, Formative and Summative Evaluation, Mixed Methods, School-Based Prevention and Health Promotion