Servitivation is a global trend in manufacturing industry that requires a challenging and complex transformation. In this context, engineering and design Product-Service System (PSS), capturing both product and service perspectives and balancing customer satisfaction and internal efficiency, are becoming more and more essential. To this purpose, the SEEM (SErvice Engineering Methodology) methodology is proposed and the SEEM Modeling toolkit supporting its implementation is presented. Lastly, this chapter describes the metholodgy and the tool implementations in a case study in an Italian manufacturing company.