The aim of our research is to develop an operational model of the behavior of designers in the domain of architecture. We hope to account for the designers’ behavior in terms of two major functionalities: Problem Structuring- establishing and transforming the parameters of the design problem; and Problem Solving- seeking a solution based on the known parameters of the design problem. In this paper, we present a formal paradigm of the designers’ behavior that is based on protocol experiments. First, the protocol experiments are briefly described and analyzed. Next, the paradigm that we have developed based on the protocol data is presented. The paradigm is elaborated in distinct categories of representation to reflect the diverse nature of knowledge employed by human designers in the architectural design problems. This is followed by a brief description of a computer program under development that we hope will operationally demonstrate the efficacy of our paradigm.