Performing product development means to simultaneously develop product systems, production processes and marketing efforts. Product Development processes are often complex as they are time dependent and contain many inter-dependencies e.g. between parts and individuals involved Due to the complexity in these processes the methods for research on integrated product development processes need to be designed differently than traditional research methods used. The study of details of totalities can work for mechanical systems but less well for complex systems. For a deeper knowledge of complex systems substantial researcher involvement and participation in real time is essential, which Insider Action Research (IAR) is designed for. IAR can be performed from the three main positions as observer, team member or project leader. The-following conclusions have been drawn (Bjork 2003): The IAR approach is beneficial in most types of development processes and projects when the aim of the research is to achieve increased knowledge and understanding. A mix of detailed and narrative descriptions of a research project provides also practitioners with an opportunity to adopt the findings. The implementation of research results would thereby become facilitated, which is an effect that most researchers as well as practitioners would benefit from.