Security has become a paramount concern due to dramatic advances of network technologies and a wide variety of new business opportunities. These advances have also brought the need for integration of computers systems to the surface, mainly for real-time, information sharing. As these systems are network-based, COTS products are predominantly used in these types of integration efforts. Since security is still a relatively new concern, it is often addressed as an afterthought in software development. Unfortunately, to ensure a high degree of security, it is imperative to address the concerns in a principled manner. Software architectures provide a unique opportunity to assess and structure the security as part of integration solution design. In this paper, we describe an approach to constructing secure integration architectures—architectural solutions to component interoperability that both satisfy known functional security policies and that specify the functionality of security mechanisms used to fulfill them.