Multinational Experiment MNE 7, Access to the Global Commons, was a complex, two-year, multinational and inter-agency effort designed to improve coalition capabilities relative to ensuring access to the global commons. We depend on space to enhance and enable a broad range of military, governmental, and commercial capabilities. However, our access to space is vulnerable to hazards and threats. So, we must adopt new strategies to assure necessary space capabilities. These strategies must be proactive, and develop the means to influence, deter, defend and mitigate the consequences of harmful actions in space. These issues are compounded by the fact that the capacity of space is finite. There is limited availability of useful orbits and consequently, they are congested. Furthermore, our reliance on space makes it a tempting target for potential actors, who may wish to negate economic or security advantages in other domains by disrupting space-enabled capabilities. A range of options exists to disrupt or deny the space, ground, and communication segments of space systems, thereby degrading space capabilities. This handbook is aimed at audiences working in a disparate range of military and civilian, specialist and generalist areas, including policy makers. Some will have considerable experience of space related issues, while others have none, so a main body of text has been created to act as a basic primer. This enables users to develop a basic, but sufficient, understanding of the key capabilities that space systems can provide, while also describing mitigation methods and the potential impacts of loss of space services.