This paper presents a research work investigating the level of maturity of New Service Development (NSD) processes of manufacturing companies for the development of product services. A preliminary Maturity Model to assess the maturity level of companies in NSD is proposed. Three case studies have been carried out, and companies were involved hands-on in a workshop to discuss ongoing projects and NSD practices. This empirical approach allowed also to touch a second issue concerning the role of external stakeholders, e.g. consultants and research centres, and of structured tools and methodologies in helping companies moving forward towards the adoption of more structured approaches to NSD. The maturity model was helpful in assessing how the case companies carry out their NSD processes, and which are the main gaps concerning the different key dimensions and elements. Such a model can support the definition of improvement actions by company managers.