Teacher Design Teams (TDTs) are professional learning communities in which teachers collaborate to (re)design innovative educational materials. TDTs can contribute to teachers’ professional growth. Furthermore, engaging teachers in the design process could create ownership, increasing the likelihood that teachers actually use the innovative materials in practice. In this study, we aimed to obtain in-depth insights into the TDT process and to identify possible links with the outcomes. We studied three cases of TDTs, collecting qualitative data from multiple perspectives. We found that the perceived outcomes of the TDTs were mixed. The leadership style appeared to play an important role in shaping the process and hence the perceived outcomes. To improve the outcomes of future TDTs, insights from this study suggest that team coaches should provide more structure and clarity during the process. At the same time, the coaches should create an atmosphere in which participants can take the initiative.