In this paper, we present a pattern-based software development method that preserves usability and security quality characteristics using a role-driven mapping of requirements analysis documents to architectural design artifacts. The quality characteristics usability and security are captured using specialized problem frames, which are patterns that serve to structure, characterize, and analyze a given software development problem. Each problem frame is equipped with a set of appropriate architectural styles and design patterns reflecting usability and security aspects. Instances of these architectural patterns constitute solutions of the initially given software development problem. We illustrate our approach by the example of a chat system.