This guide aims to equip public servants with the necessary knowledge to understand what the Blockchain architecture is, the implications it could have on government services, and the opportunities and challenges governments may face as a result. It also aims to provide information on what Blockchain technology is not, and areas where its application may not be useful. Section I defines Blockchain technology and discusses the various ways governments have begun to react and adapt to the emergence of Blockchain technology. This includes discussing the landscape of current Blockchain initiatives as well of the various types of use cases that may be the most relevant in the public sector. Section II focuses on the challenges that Blockchain technology poses to public administrations, as well as its limitations which may make render the technology unsuitable for certain uses. Finally, a series of appendices provide case studies as well as some more technical discussions of specific aspects of Blockchain technology.