This paper shows how the principles of programming methodology and language design can help solve the problem of specifying and creating interactive display interfaces for software systems. Abstraction techniques, such as abstract data types, can support both the specification of display interfaces and the implementation of those interfaces in a variety of styles. These abstraction techniques also guide the organization of software systems that will use display interfaces. We are developing a system that includes specifications, interface description tools, prototype organizations, and runtime support. The emphasis is on flexibility and on the separation of policy from particular instances. Preliminary results from implementations in a prot...