"Space Security 2011: Building on the Past, Stepping towards the Future" is the tenth annual conference held by UNIDIR on the issue of space security, the peaceful uses of outer space and the prevention of an arms race in outer space. This conference focused on current and emerging threats in the space domain and the ongoing efforts to address them, the technical aspects of ensuring space security and enabling regimes supporting that end, the necessity and benefits of cooperation among the many actors now involved in space and space-related issues, and identifying and engaging those actors that will be necessary to the success of regimes set up to protect and encourage the long-term safety and accessibility of space.