Interaction design patterns are a proven way to communicate good design. However, current pattern collections are not sufficiently powerful and generative to be used as a guide for designing an entire application such as those used in complex business environments. In this project we built and validated interaction design patterns that serve as the specification for the redesign of an application at ZKB. Additionally, they were integrated into a pattern language, as a ruleset for human–computer interaction (HCI) non-professionals to continue development of the application. We demonstrate how individual phases in the redesign of an application can be matched with the process of creating an interaction design pattern language. To facilitate the writing of individual interaction design patterns as well as the development of the pattern language as a whole, a combination of user interviews, controlled experiments and analytical methods has been applied successfully.