Mass customization is a business approach aimed at the low-cost production of customized goods and services. It relies on 'horizontalization', platform thinking and modularity, but how can these concepts be applied in a fast-changing service environment in which both the product and production processes are predominantly intangible?The study proposes an integrated innovation management system to effectively manage the innovation process in such an environment. A so-called 'SLIM' model is developed based on an in-depth case study at an incumbent telecom operator in the midst of a transition toward a mass-customized service company. Literature on business modeling, service marketing and new service development plays a major role, and IT-originating concepts of business componentization and release management are transformed to the business level. All in all, the SLIM model implies a major shift for organizations in how they position, design and organize the innovation process.Rob Reitsma holds an engineering degree and has more than 20 years' experience in the telecom/ICT service industry. He fulfilled various managerial and professional roles on the intersection of product management/marketing and technology/process management.