AbstractThis paper presents an abstract architecture capturing the most essential characteristics of security architectures for the kind of access control required in multi-agent systems. A security architecture is usually component based; it is dynamically extensible, reflective, and should be able to support a variety of policy strategies and enforcement mechanisms. Therefore, in designing and implementing such an architecture, it is important to accurately describe its structure, components, and their interactions; and we should also provide support for verifying properties that the architecture must satisfy. The abstract Dynamic Access Control Architecture, or DACA, we propose provides the flexibility to express several complex characteristics abstractly, ultimately resulting in a more structured foundation for implementing security architectures for access control.