Trustworthiness can no longer be predicted by building software systems from discrete, isolated pieces that address static requirements within planned cost and schedule. Each new or updated component joins an existing operational environment and must merge with that legacy to form an operational whole. Today’s technology must support an operating environment that is driven by business goals and organizational needs instead of a predefined infrastructure that functions within established technology constraints. The operating environment can be geographically and managerially distributed and dynamically changing. Few businesses can stop to make changes and then restart. This introduction discusses the effects of the changing operational environment on the development of secure systems.