Due to a dynamically changing market environment, an effective management of new product development processes poses a critical success factor for manufacturers of complex products. An important problem in new product development is a frequent lack of shared understanding and collective action of the actors. This research shows ways on how to mitigate this problem by conceptualisation, implementation and evaluation of a theory-driven co-active system. Within this thesis, a theoretical framework containing two conceptual research models as well as several guiding principles providing qualitative directions for system design is derived. On grounds of the theoretical framework, a co-active system employing product development process reference modelling and Web 2.0 technologies is constructed. Using the co-active system, product development process actors can participate in further development and application of the process reference model. In this way, the co-active system supports the work of a unique community of process experts. The system constructed is tested within the product development community of a large commercial vehicle manufacturer. Using quantitative and qualitative evaluation methods, the appropriateness of the theoretical framework and the co-active system is shown.