Design Science Research (DSR) has reached a significant impact on scholar’s research work around the globe in the information systems domain. DSR is an important IS research paradigm for creating descriptive and prescriptive knowledge concerning the artificial construction of today’s reality in the interrelation between the social and the technological sub-system. Various prior research has decisively defined and structured DSR in order to derive rigorously relevant contributions in terms of frameworks and methodologies. This paper contributes to this discourse from a research in action point of view by investigating critical activities within the design science phases and when passing from one to the next DSR cycle. For that purpose we elaborate critical DSR activities and demonstrate their effective execution along four DSR in action examples to provide guidance and best practices for design science projects seeking for rigor and relevance.