Problem space, social space, institutional space (PSI) is a framework and a theory of design for modeling design contexts, whose roots are in the reflection on our projects and studies over last decades; it took shape in the last seven years and has been evaluated extensively. This article traces the drivers for its development into a framework that provides the dimensions of describing design contexts in their variety and can be used to integrate other models and theories at different levels of granularity to explain intricate design situations. We have tested the framework on more than 170 cases to model, explain, and inform a variety of design situations. We describe several of them. The collected evidence supports the potential utility of PSI. Future work is required to continue develop the framework and form patterns of use that will help characterize and improve design processes.