The development of space resources activities is happening now. In the absence of a clear framework to govern these activities there is a need to formulate such a framework in line with existing treaty obligations, in order to enable, support and coordinate the use of space resources in a manner that is acceptable for all stakeholders. This book provides a unique and comprehensive coverage of the work of The Hague International Space Resources Governance Group, established in 2016 with the purpose of assessing the need and laying the groundwork for such a framework. The Commentary contains the text, explanation, legal basis and alternatives discussed for each of the 20 Building Blocks that were adopted by the Working Group in 2019 and that could potentially form part of a future governance framework for space resource activities. The book is a useful reference tool for States, international organisations, industry, space agencies, scientists, academics and students in space law and policy interested in this new era of use and exploration of outer space.