Platform as a Service (PaaS) solutions are changing the way software is produced, distributed, used, and priced. However, there has been little research into understanding the dynamics of PaaS business models and how these business models should be designed to establish a flourishing ecosystem around these platforms. Using design science research (DSR) we first identified the main design elements of PaaS business models as well as their relationships by investigating 24 PaaS providers. The resulting classification scheme as well as the qualitative systems dynamics model (in form of a causal loop diagram (CLD)) facilitates a better understanding of the adoption dynamics of PaaS business models. By focusing on the adoption dynamics of PaaS business models, our research goes beyond previous approaches for studying PaaS. 1