In companies more and more knowledge is prepared and directly handed over by colleagues to colleagues. These multiplier concepts are widely used across sectors. This handbook demonstrates how these internal training sessions may be designed and carried out competently. Another focus is the external professional development, the selection and evaluation of trainers and training sessions. The Deutsche Gesellschaft für Personalführung e.V. (DGFP, German Association for Human resource management), has offered specialists and middle managers, trainers and educators the course "Train the trainer" for 10 years; and this course is the basis for this publication. In the practical part of the handbook graduates of the "Train the trainer" programme present company projects, which they could realise successfully with their acquired competences. The final chapter presents tolls for the training practice, which support target and transfer-orientated learning processes.