集体安全是一种保障所有国家生存与国际和平的制度。在这种机制下，每个参与国都认为破坏和平是对所有参与国共同的挑战，也即参与国认为其他国家的安全是所有国家的安全。

集体安全概念的假设是，国家将放弃使用武力或是以武力为威胁以求达成国家利益及目标，所有国家对为违反此一原则的侵略国家进行集体制裁，以维持国际和平及秩序。

集体安全是国联和联合国的主要宗旨之一。

原华沙条约组织、现在的集体安全条约组织和北大西洋公约组织则是区域性的集体安全组织。

Collective security can be understood as a security arrangement, political, regional, or global, in which each state in the system accepts that the security of one is the concern of all, and therefore commits to a collective response to threats to, and breaches to peace. Collective security is more ambitious than systems of alliance security or collective defense in that it seeks to encompass the totality of states within a region or indeed globally, and to address a wide range of possible threats. While collective security is an idea with a long history, its implementation in practice has proved problematic. Several prerequisites have to be met for it to have a chance of working.