Government as a Platform (GaaP) represents the notion that governments significantly benefit from the adoption of platform concepts from the private sector. While several governments are already implementing this notion, there is an insufficient understanding of what actually constitutes a successful GaaP approach. We apply a design science research strategy and, based on interviews with 26 experts and a survey, iteratively design and evaluate 10 guiding principles for GaaP. The principles show how technological and governance aspects complement each other and which platform concepts constitute GaaP. Our research has implications for scholars towards a detailed conceptualization of GaaP, while practitioners can use the principles as guidelines for implementation.